diff --git a/include/xrpl/hook/HookAPI.h b/include/xrpl/hook/HookAPI.h
index fd8e46271..7e2bf0f82 100644
--- a/include/xrpl/hook/HookAPI.h
+++ b/include/xrpl/hook/HookAPI.h
@@ -329,14 +329,15 @@ private:
         int32_t,
         parse_error>
     get_stobject_length(
-        unsigned char* start,     // in - begin iterator
-        unsigned char* maxptr,    // in - end iterator
-        int& type,                // out - populated by serialized type code
-        int& field,               // out - populated by serialized field code
-        int& payload_start,       // out - the start of actual payload data for
-                                  // this type
-        int& payload_length,      // out - the length of actual payload data for
-                                  // this type
+        unsigned char* start,   // in - begin iterator
+        unsigned char* maxptr,  // in - end iterator
+        int& type,              // out - populated by serialized type code
+        int& field,             // out - populated by serialized field code
+        int& payload_start,     // out - the start of actual payload data for
+                                // this type
+        int& payload_length,    // out - the length of actual payload data for
+                                // this type
+        Rules const& rules,
         int recursion_depth = 0)  // used internally
         const;
 };
diff --git a/include/xrpl/protocol/Feature.h b/include/xrpl/protocol/Feature.h
index 823bc03a2..a04c9988d 100644
--- a/include/xrpl/protocol/Feature.h
+++ b/include/xrpl/protocol/Feature.h
@@ -80,7 +80,7 @@ namespace detail {
 // Feature.cpp. Because it's only used to reserve storage, and determine how
 // large to make the FeatureBitset, it MAY be larger. It MUST NOT be less than
 // the actual number of amendments. A LogicError on startup will verify this.
-static constexpr std::size_t numFeatures = 110;
+static constexpr std::size_t numFeatures = 111;
 
 /** Amendments that this server supports and the default voting behavior.
    Whether they are enabled depends on the Rules defined in the validated
diff --git a/include/xrpl/protocol/detail/features.macro b/include/xrpl/protocol/detail/features.macro
index 1dfe26779..57c69f671 100644
--- a/include/xrpl/protocol/detail/features.macro
+++ b/include/xrpl/protocol/detail/features.macro
@@ -29,6 +29,7 @@
 // If you add an amendment here, then do not forget to increment `numFeatures`
 // in include/xrpl/protocol/Feature.h.
 
+XRPL_FEATURE(HookAPISerializedType240,   Supported::yes, VoteBehavior::DefaultNo)
 XRPL_FEATURE(PermissionedDomains,        Supported::no,  VoteBehavior::DefaultNo)
 XRPL_FEATURE(DynamicNFT,                 Supported::no,  VoteBehavior::DefaultNo)
 XRPL_FEATURE(Credentials,                Supported::no,  VoteBehavior::DefaultNo)
diff --git a/src/libxrpl/protocol/STTx.cpp b/src/libxrpl/protocol/STTx.cpp
index 8d45f54cd..7758a6ae1 100644
--- a/src/libxrpl/protocol/STTx.cpp
+++ b/src/libxrpl/protocol/STTx.cpp
@@ -487,7 +487,7 @@ isMemoOkay(STObject const& st, std::string& reason)
             if (!paramObj->isFieldPresent(sfHookParameterValue) ||
                 paramObj->getFieldVL(sfHookParameterValue).size() > maxVal)
             {
-                reason = "HookParameterValue cannot exceed 128 bytes.";
+                reason = "HookParameterValue cannot exceed 256 bytes.";
                 return false;
             }
         }
diff --git a/src/test/app/SetHook_test.cpp b/src/test/app/SetHook_test.cpp
index 5caf6b33b..2cfe8ae14 100644
--- a/src/test/app/SetHook_test.cpp
+++ b/src/test/app/SetHook_test.cpp
@@ -10951,6 +10951,186 @@ public:
 
         // invoke the hook
         env(pay(bob, alice, XRP(1)), M("test sto_validate"), fee(XRP(1)));
+
+        {
+            // test STIs
+            TestHook hook = wasm[R"[test.hook](
+                #include <stdint.h>
+                extern int32_t _g       (uint32_t id, uint32_t maxiter);
+                #define GUARD(maxiter) _g((1ULL << 31U) + __LINE__, (maxiter)+1)
+                extern int64_t accept   (uint32_t read_ptr, uint32_t read_len, int64_t error_code);
+                extern int64_t rollback (uint32_t read_ptr, uint32_t read_len, int64_t error_code);
+                extern int64_t sto_validate(uint32_t, uint32_t);
+                extern int64_t otxn_param(uint32_t, uint32_t, uint32_t, uint32_t);
+                #define ASSERT(x)\
+                    if (!(x))\
+                        rollback((uint32_t)#x, sizeof(#x), __LINE__);
+                #define SBUF(x) (uint32_t)(x), sizeof(x)
+
+                uint8_t buf[1000];
+                int64_t hook(uint32_t reserved)
+                {
+                    _g(1,1);
+
+                    int64_t size = otxn_param(SBUF(buf), "V", 1);
+                    int64_t result = sto_validate(buf, size);
+
+                    accept(0,0,result);
+                }
+            )[test.hook]"];
+
+            for (auto feature : {
+                     features - featureHookAPISerializedType240,
+                     features | featureHookAPISerializedType240,
+                 })
+            {
+                Env env{*this, feature};
+
+                env.fund(XRP(10000), alice, bob);
+                env.close();
+
+                auto hasEnabled = env.current()->rules().enabled(
+                    featureHookAPISerializedType240);
+
+                // install the hook on alice
+                env(ripple::test::jtx::hook(
+                        alice, {{hso(hook, overrideFlag)}}, 0),
+                    M("set sto_validate"),
+                    HSFEE);
+                env.close();
+
+                // invoke the hook
+                auto buildTx = [&](std::string value) {
+                    auto payJv = pay(bob, alice, XRP(1));
+
+                    Json::Value params{Json::arrayValue};
+                    auto& param = params[0U][jss::HookParameter];
+                    param[jss::HookParameterName] = strHex(std::string("V"));
+                    param[jss::HookParameterValue] = value;
+                    payJv[jss::HookParameters] = params;
+                    return payJv;
+                };
+
+                auto testSTI = [&](std::string value, bool expectedResult) {
+                    auto tx = buildTx(value);
+                    env(tx, M("test STI"), fee(XRP(1)));
+                    env.close();
+
+                    auto const result = env.meta()
+                                            ->getFieldArray(sfHookExecutions)[0]
+                                            .getFieldU64(sfHookReturnCode);
+                    if (expectedResult)
+                        BEAST_EXPECTS(result == 1, value);
+                    else
+                        BEAST_EXPECTS(result == 0, value);
+                };
+
+                // STI_UINT32
+                testSTI("2200000001", true);
+                // STI_UINT64
+                testSTI("301100000000000003E8", true);
+                // STI_UINT128
+                testSTI("4100000000000000000000000000000000", true);
+                // STI_UINT256
+                testSTI(
+                    "5060000000000000000000000000000000000000000000000000000000"
+                    "0000000000",
+                    true);
+                // STI_AMOUNT
+                testSTI("614000000000000064", true);
+                testSTI(
+                    "61D5038D7EA4C680000000000000000000000000005553440000000000"
+                    "AE123A8556F3CF91154711376AFB0F894F832B3D",
+                    true);
+                // STI_VL
+                testSTI("7504DEADBEEF", true);
+                // STI_ACCOUNT
+                testSTI("8114AE123A8556F3CF91154711376AFB0F894F832B3D", true);
+                // STI_NUMBER
+                // testSTI("000400000000000000000000000000000001", true);
+                // STI_OBJECT
+                testSTI("E05C22000000017504DEADBEEFE1", true);
+                // STI_ARRAY
+                testSTI(
+                    "F05CE05B614000000000000064E1E05B61D5038D7EA4C6800000000000"
+                    "00000000000000005553440000000000AE123A8556F3CF91154711376A"
+                    "FB0F894F832B3DE1F1",
+                    true);
+                // STI_UINT8
+                testSTI("00101003", true);
+                // STI_UINT160
+                testSTI("01110000000000000000000000000000000000000000", true);
+                // STI_PATHSET
+                testSTI(
+                    "0112300000000000000000000000005553440000000000AE123A8556F3"
+                    "CF91154711376AFB0F894F832B3D00",
+                    hasEnabled);
+                testSTI(
+                    "0112310A20B3C85F482532A9578DBB3950B85CA06594D1000000000000"
+                    "00000000000042544300000000000A20B3C85F482532A9578DBB3950B8"
+                    "5CA06594D13000000000000000000000000055534400000000000A20B3"
+                    "C85F482532A9578DBB3950B85CA06594D1FF3157180C769B66D942EE69"
+                    "E6DCC940CA48D82337AD00000000000000000000000042544300000000"
+                    "0057180C769B66D942EE69E6DCC940CA48D82337AD1000000000000000"
+                    "0000000000000000000000000030000000000000000000000000555344"
+                    "00000000000A20B3C85F482532A9578DBB3950B85CA06594D100",
+                    hasEnabled);
+                // STI_VECTOR256
+                testSTI(
+                    "0013634000000000000000000000000000000000000000000000000000"
+                    "0000000000000000000000000000000000000000000000000000000000"
+                    "00000000000000000000",
+                    true);
+                // STI_UINT96
+                // testSTI("000400000000000000000000000000000001", true);
+                // STI_UINT192
+                // testSTI("000400000000000000000000000000000001", true);
+                // STI_UINT384
+                // testSTI("000400000000000000000000000000000001", true);
+                // STI_UINT512
+                // testSTI("000400000000000000000000000000000001", true);
+                // STI_ISSUE
+                testSTI(
+                    "03180000000000000000000000005553440000000000AE123A8556F3CF"
+                    "91154711376AFB0F894F832B3D",
+                    hasEnabled);
+                testSTI(
+                    "03180000000000000000000000000000000000000000", hasEnabled);
+                // STI_XCHAIN_BRIDGE
+                /// Native-Native
+                testSTI(
+                    "011914AE123A8556F3CF91154711376AFB0F894F832B3D000000000000"
+                    "000000000000000000000000000014AE123A8556F3CF91154711376AFB"
+                    "0F894F832B3D0000000000000000000000000000000000000000",
+                    hasEnabled);
+                /// IOU-Native
+                testSTI(
+                    "011914AE123A8556F3CF91154711376AFB0F894F832B3D000000000000"
+                    "0000000000005553440000000000AE123A8556F3CF91154711376AFB0F"
+                    "894F832B3D14AE123A8556F3CF91154711376AFB0F894F832B3D000000"
+                    "0000"
+                    "000000000000000000000000000000",
+                    hasEnabled);
+                /// Native-IOU
+                testSTI(
+                    "011914AE123A8556F3CF91154711376AFB0F894F832B3D000000000000"
+                    "0000000000005553440000000000AE123A8556F3CF91154711376AFB0F"
+                    "894F832B3D14AE123A8556F3CF91154711376AFB0F894F832B3D000000"
+                    "0000000000000000000000000000000000",
+                    hasEnabled);
+                /// IOU-IOU
+                testSTI(
+                    "011914AE123A8556F3CF91154711376AFB0F894F832B3D000000000000"
+                    "0000000000005553440000000000AE123A8556F3CF91154711376AFB0F"
+                    "894F832B3D14AE123A8556F3CF91154711376AFB0F894F832B3D000000"
+                    "0000000000000000005553440000000000AE123A8556F3CF9115471137"
+                    "6AFB0F894F832B3D",
+                    hasEnabled);
+                // STI_CURRENCY
+                testSTI(
+                    "011A0000000000000000000000005553440000000000", hasEnabled);
+            }
+        }
     }
 
     void
diff --git a/src/test/app/SetHook_wasm.h b/src/test/app/SetHook_wasm.h
index faf21ac31..882eac56e 100644
--- a/src/test/app/SetHook_wasm.h
+++ b/src/test/app/SetHook_wasm.h
@@ -16916,7 +16916,7 @@ std::map<std::string, std::vector<uint8_t>> wasm = {
          0x64U, 0xE1U, 0xF1U,
      }},
 
-    /* ==== WASM: 79 ==== */
+    /* ==== WASM: 80 ==== */
     {R"[test.hook](
             #include <stdint.h>
             extern int32_t _g       (uint32_t id, uint32_t maxiter);
@@ -17089,7 +17089,7 @@ std::map<std::string, std::vector<uint8_t>> wasm = {
          0x54U, 0x5FU, 0x45U, 0x58U, 0x49U, 0x53U, 0x54U, 0x00U,
      }},
 
-    /* ==== WASM: 80 ==== */
+    /* ==== WASM: 81 ==== */
     {R"[test.hook](
             #include <stdint.h>
             extern int32_t _g       (uint32_t id, uint32_t maxiter);
@@ -17237,7 +17237,161 @@ std::map<std::string, std::vector<uint8_t>> wasm = {
          0x30U, 0x00U, 0x22U, 0x00U, 0x00U, 0x00U, 0x00U,
      }},
 
-    /* ==== WASM: 81 ==== */
+    /* ==== WASM: 82 ==== */
+    {R"[test.hook](
+                #include <stdint.h>
+                extern int32_t _g       (uint32_t id, uint32_t maxiter);
+                #define GUARD(maxiter) _g((1ULL << 31U) + __LINE__, (maxiter)+1)
+                extern int64_t accept   (uint32_t read_ptr, uint32_t read_len, int64_t error_code);
+                extern int64_t rollback (uint32_t read_ptr, uint32_t read_len, int64_t error_code);
+                extern int64_t sto_validate(uint32_t, uint32_t);
+                extern int64_t otxn_param(uint32_t, uint32_t, uint32_t, uint32_t);
+                #define ASSERT(x)\
+                    if (!(x))\
+                        rollback((uint32_t)#x, sizeof(#x), __LINE__);
+                #define SBUF(x) (uint32_t)(x), sizeof(x)
+
+                uint8_t buf[1000];
+                int64_t hook(uint32_t reserved)
+                {
+                    _g(1,1);
+
+                    int64_t size = otxn_param(SBUF(buf), "V", 1);
+                    int64_t result = sto_validate(buf, size);
+
+                    accept(0,0,result);
+                }
+            )[test.hook]",
+     {
+         0x00U, 0x61U, 0x73U, 0x6DU, 0x01U, 0x00U, 0x00U, 0x00U, 0x01U, 0x21U,
+         0x05U, 0x60U, 0x02U, 0x7FU, 0x7FU, 0x01U, 0x7FU, 0x60U, 0x04U, 0x7FU,
+         0x7FU, 0x7FU, 0x7FU, 0x01U, 0x7EU, 0x60U, 0x02U, 0x7FU, 0x7FU, 0x01U,
+         0x7EU, 0x60U, 0x03U, 0x7FU, 0x7FU, 0x7EU, 0x01U, 0x7EU, 0x60U, 0x01U,
+         0x7FU, 0x01U, 0x7EU, 0x02U, 0x3BU, 0x04U, 0x03U, 0x65U, 0x6EU, 0x76U,
+         0x02U, 0x5FU, 0x67U, 0x00U, 0x00U, 0x03U, 0x65U, 0x6EU, 0x76U, 0x0AU,
+         0x6FU, 0x74U, 0x78U, 0x6EU, 0x5FU, 0x70U, 0x61U, 0x72U, 0x61U, 0x6DU,
+         0x00U, 0x01U, 0x03U, 0x65U, 0x6EU, 0x76U, 0x0CU, 0x73U, 0x74U, 0x6FU,
+         0x5FU, 0x76U, 0x61U, 0x6CU, 0x69U, 0x64U, 0x61U, 0x74U, 0x65U, 0x00U,
+         0x02U, 0x03U, 0x65U, 0x6EU, 0x76U, 0x06U, 0x61U, 0x63U, 0x63U, 0x65U,
+         0x70U, 0x74U, 0x00U, 0x03U, 0x03U, 0x02U, 0x01U, 0x04U, 0x05U, 0x03U,
+         0x01U, 0x00U, 0x02U, 0x06U, 0x27U, 0x06U, 0x7FU, 0x01U, 0x41U, 0xF0U,
+         0x8FU, 0x04U, 0x0BU, 0x7FU, 0x00U, 0x41U, 0xEAU, 0x0FU, 0x0BU, 0x7FU,
+         0x00U, 0x41U, 0x80U, 0x08U, 0x0BU, 0x7FU, 0x00U, 0x41U, 0xF0U, 0x8FU,
+         0x04U, 0x0BU, 0x7FU, 0x00U, 0x41U, 0x80U, 0x08U, 0x0BU, 0x7FU, 0x00U,
+         0x41U, 0x80U, 0x08U, 0x0BU, 0x07U, 0x08U, 0x01U, 0x04U, 0x68U, 0x6FU,
+         0x6FU, 0x6BU, 0x00U, 0x04U, 0x0AU, 0xC4U, 0x80U, 0x00U, 0x01U, 0xC0U,
+         0x80U, 0x00U, 0x01U, 0x01U, 0x7EU, 0x41U, 0x01U, 0x41U, 0x01U, 0x10U,
+         0x80U, 0x80U, 0x80U, 0x80U, 0x00U, 0x1AU, 0x41U, 0x00U, 0x41U, 0x00U,
+         0x41U, 0x80U, 0x88U, 0x80U, 0x80U, 0x00U, 0x41U, 0x80U, 0x88U, 0x80U,
+         0x80U, 0x00U, 0x41U, 0xE8U, 0x07U, 0x41U, 0xE8U, 0x8FU, 0x80U, 0x80U,
+         0x00U, 0x41U, 0x01U, 0x10U, 0x81U, 0x80U, 0x80U, 0x80U, 0x00U, 0xA7U,
+         0x10U, 0x82U, 0x80U, 0x80U, 0x80U, 0x00U, 0x10U, 0x83U, 0x80U, 0x80U,
+         0x80U, 0x00U, 0x1AU, 0x20U, 0x01U, 0x0BU, 0x0BU, 0xF8U, 0x07U, 0x02U,
+         0x00U, 0x41U, 0x80U, 0x08U, 0x0BU, 0xE8U, 0x07U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U,
+         0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x00U, 0x41U, 0xE8U,
+         0x0FU, 0x0BU, 0x02U, 0x56U, 0x00U,
+     }},
+
+    /* ==== WASM: 83 ==== */
     {R"[test.hook](
             #include <stdint.h>
             extern int32_t _g       (uint32_t id, uint32_t maxiter);
@@ -17334,7 +17488,7 @@ std::map<std::string, std::vector<uint8_t>> wasm = {
          0x3DU, 0x20U, 0x30U, 0x00U,
      }},
 
-    /* ==== WASM: 82 ==== */
+    /* ==== WASM: 84 ==== */
     {R"[test.hook](
             #include <stdint.h>
             extern int32_t _g       (uint32_t id, uint32_t maxiter);
@@ -17393,7 +17547,7 @@ std::map<std::string, std::vector<uint8_t>> wasm = {
          0x4FU, 0x46U, 0x5FU, 0x42U, 0x4FU, 0x55U, 0x4EU, 0x44U, 0x53U, 0x00U,
      }},
 
-    /* ==== WASM: 83 ==== */
+    /* ==== WASM: 85 ==== */
     {R"[test.hook](
             #include <stdint.h>
             extern int32_t _g       (uint32_t id, uint32_t maxiter);
@@ -17452,7 +17606,7 @@ std::map<std::string, std::vector<uint8_t>> wasm = {
          0x4EU, 0x44U, 0x53U, 0x00U,
      }},
 
-    /* ==== WASM: 84 ==== */
+    /* ==== WASM: 86 ==== */
     {R"[test.hook](
             #include <stdint.h>
             extern int32_t _g       (uint32_t id, uint32_t maxiter);
@@ -19281,7 +19435,7 @@ std::map<std::string, std::vector<uint8_t>> wasm = {
          0x53U, 0x4DU, 0x41U, 0x4CU, 0x4CU, 0x00U,
      }},
 
-    /* ==== WASM: 85 ==== */
+    /* ==== WASM: 87 ==== */
     {R"[test.hook](
             #include <stdint.h>
             extern int32_t _g       (uint32_t id, uint32_t maxiter);
@@ -20898,7 +21052,7 @@ std::map<std::string, std::vector<uint8_t>> wasm = {
          0x2CU, 0x20U, 0x30U, 0x2CU, 0x20U, 0x30U, 0x29U, 0x29U, 0x00U,
      }},
 
-    /* ==== WASM: 86 ==== */
+    /* ==== WASM: 88 ==== */
     {R"[test.hook](
             #include <stdint.h>
             extern int32_t _g       (uint32_t id, uint32_t maxiter);
@@ -23831,7 +23985,7 @@ std::map<std::string, std::vector<uint8_t>> wasm = {
          0x4FU, 0x4FU, 0x5FU, 0x53U, 0x4DU, 0x41U, 0x4CU, 0x4CU, 0x00U,
      }},
 
-    /* ==== WASM: 87 ==== */
+    /* ==== WASM: 89 ==== */
     {R"[test.hook](
             #include <stdint.h>
             extern int32_t _g       (uint32_t id, uint32_t maxiter);
@@ -25796,7 +25950,7 @@ std::map<std::string, std::vector<uint8_t>> wasm = {
          0x54U, 0x4FU, 0x4FU, 0x5FU, 0x53U, 0x4DU, 0x41U, 0x4CU, 0x4CU, 0x00U,
      }},
 
-    /* ==== WASM: 88 ==== */
+    /* ==== WASM: 90 ==== */
     {R"[test.hook](
             #include <stdint.h>
             extern int32_t _g       (uint32_t id, uint32_t maxiter);
@@ -26081,7 +26235,7 @@ std::map<std::string, std::vector<uint8_t>> wasm = {
          0x29U, 0x20U, 0x3DU, 0x3DU, 0x20U, 0x30U, 0x00U,
      }},
 
-    /* ==== WASM: 89 ==== */
+    /* ==== WASM: 91 ==== */
     {R"[test.hook](
             #include <stdint.h>
             extern int32_t _g(uint32_t, uint32_t);
@@ -26668,7 +26822,7 @@ std::map<std::string, std::vector<uint8_t>> wasm = {
          0x4EU, 0x5FU, 0x46U, 0x41U, 0x49U, 0x4CU, 0x55U, 0x52U, 0x45U, 0x00U,
      }},
 
-    /* ==== WASM: 90 ==== */
+    /* ==== WASM: 92 ==== */
     {R"[test.hook](
             #include <stdint.h>
             extern int32_t _g       (uint32_t id, uint32_t maxiter);
@@ -26697,7 +26851,7 @@ std::map<std::string, std::vector<uint8_t>> wasm = {
          0x0BU,
      }},
 
-    /* ==== WASM: 91 ==== */
+    /* ==== WASM: 93 ==== */
     {R"[test.hook](
             #include <stdint.h>
             extern int32_t _g       (uint32_t id, uint32_t maxiter);
@@ -26729,7 +26883,7 @@ std::map<std::string, std::vector<uint8_t>> wasm = {
          0x20U, 0x52U, 0x65U, 0x6AU, 0x65U, 0x63U, 0x74U, 0x65U, 0x64U, 0x00U,
      }},
 
-    /* ==== WASM: 92 ==== */
+    /* ==== WASM: 94 ==== */
     {R"[test.hook](
             (module
               (type (;0;) (func (param i32 i32 i64) (result i64)))
@@ -26756,7 +26910,7 @@ std::map<std::string, std::vector<uint8_t>> wasm = {
          0x41U, 0x00U, 0x41U, 0x00U, 0x42U, 0x00U, 0x10U, 0x00U, 0x0BU,
      }},
 
-    /* ==== WASM: 93 ==== */
+    /* ==== WASM: 95 ==== */
     {R"[test.hook](
             (module
               (type (;0;) (func (param i32 i32) (result i32)))
@@ -26809,7 +26963,7 @@ std::map<std::string, std::vector<uint8_t>> wasm = {
          0x00U, 0x1AU, 0x0BU,
      }},
 
-    /* ==== WASM: 94 ==== */
+    /* ==== WASM: 96 ==== */
     {R"[test.hook](
             #include <stdint.h>
             extern int32_t _g       (uint32_t id, uint32_t maxiter);
@@ -33452,7 +33606,7 @@ std::map<std::string, std::vector<uint8_t>> wasm = {
          0x39U, 0x30U, 0x31U, 0x32U, 0x33U, 0x00U,
      }},
 
-    /* ==== WASM: 95 ==== */
+    /* ==== WASM: 97 ==== */
     {R"[test.hook](
             #include <stdint.h>
             extern int32_t _g           (uint32_t id, uint32_t maxiter);
@@ -33498,7 +33652,7 @@ std::map<std::string, std::vector<uint8_t>> wasm = {
          0x0BU, 0x06U, 0x76U, 0x61U, 0x6CU, 0x75U, 0x65U, 0x00U,
      }},
 
-    /* ==== WASM: 96 ==== */
+    /* ==== WASM: 98 ==== */
     {R"[test.hook](
             #include <stdint.h>
             extern int32_t _g       (uint32_t id, uint32_t maxiter);
diff --git a/src/xrpld/app/hook/detail/HookAPI.cpp b/src/xrpld/app/hook/detail/HookAPI.cpp
index 71f4aadca..15be95e4c 100644
--- a/src/xrpld/app/hook/detail/HookAPI.cpp
+++ b/src/xrpld/app/hook/detail/HookAPI.cpp
@@ -355,7 +355,14 @@ HookAPI::sto_validate(Bytes const& data) const
     {
         int type = -1, field = -1, payload_start = -1, payload_length = -1;
         auto const length = get_stobject_length(
-            upto, end, type, field, payload_start, payload_length, 0);
+            upto,
+            end,
+            type,
+            field,
+            payload_start,
+            payload_length,
+            hookCtx.applyCtx.view().rules(),
+            0);
         if (!length)
             return 0;
         upto += length.value();
@@ -389,7 +396,14 @@ HookAPI::sto_subfield(Bytes const& data, uint32_t field_id) const
     {
         int type = -1, field = -1, payload_start = -1, payload_length = -1;
         auto const length = get_stobject_length(
-            upto, end, type, field, payload_start, payload_length, 0);
+            upto,
+            end,
+            type,
+            field,
+            payload_start,
+            payload_length,
+            hookCtx.applyCtx.view().rules(),
+            0);
         if (!length)
             return Unexpected(PARSE_ERROR);
         if ((type << 16) + field == field_id)
@@ -464,7 +478,14 @@ HookAPI::sto_subarray(Bytes const& data, uint32_t index_id) const
     {
         int type = -1, field = -1, payload_start = -1, payload_length = -1;
         auto const length = get_stobject_length(
-            upto, end, type, field, payload_start, payload_length, 0);
+            upto,
+            end,
+            type,
+            field,
+            payload_start,
+            payload_length,
+            hookCtx.applyCtx.view().rules(),
+            0);
         if (!length)
             return Unexpected(PARSE_ERROR);
 
@@ -530,6 +551,7 @@ HookAPI::sto_emplace(
             field,
             payload_start,
             payload_length,
+            hookCtx.applyCtx.view().rules(),
             0);
         if (!length)
             return Unexpected(PARSE_ERROR);
@@ -565,7 +587,14 @@ HookAPI::sto_emplace(
     {
         int type = -1, field = -1, payload_start = -1, payload_length = -1;
         auto const length = get_stobject_length(
-            upto, end, type, field, payload_start, payload_length, 0);
+            upto,
+            end,
+            type,
+            field,
+            payload_start,
+            payload_length,
+            hookCtx.applyCtx.view().rules(),
+            0);
         if (!length)
             return Unexpected(PARSE_ERROR);
         if ((type << 16) + field == field_id)
@@ -2998,12 +3027,20 @@ HookAPI::get_stobject_length(
     int& payload_start,  // out - the start of actual payload data for this type
     int& payload_length,  // out - the length of actual payload data for this
                           // type
+    Rules const& rules,
     int recursion_depth)  // used internally
     const
 {
     if (recursion_depth > 10)
         return Unexpected(pe_excessive_nesting);
 
+    uint16_t max_sti_type = rules.enabled(featureHookAPISerializedType240)
+        ? STI_CURRENCY
+        : STI_VECTOR256;
+
+    if (type > max_sti_type)
+        return pe_unknown_type_early;
+
     unsigned char* end = maxptr;
     unsigned char* upto = start;
     int high = *upto >> 4;
@@ -3055,14 +3092,20 @@ HookAPI::get_stobject_length(
     auto const& fieldObj = ripple::SField::getField;
     */
 
-    if (type < 1 || type > 19 || (type >= 9 && type <= 13))
+    // type 10~13 are reserved
+    if (type < 1 || max_sti_type < type || (10 <= type && type <= 13))
         return Unexpected(pe_unknown_type_early);
 
+    // not supported types
+    if (type == STI_NUMBER || type == STI_UINT96 || type == STI_UINT192 ||
+        type == STI_UINT384 || type == STI_UINT512)
+        return pe_unknown_type_early;
+
     bool is_vl =
-        (type == SerializedTypeID::STI_ACCOUNT ||
-         type == SerializedTypeID::STI_VL ||
-         type == SerializedTypeID::STI_PATHSET ||
-         type == SerializedTypeID::STI_VECTOR256);
+        (type == STI_ACCOUNT || type == STI_VL ||
+         (type == STI_PATHSET &&
+          !rules.enabled(featureHookAPISerializedType240)) ||
+         type == STI_VECTOR256);
 
     int length = -1;
     if (is_vl)
@@ -3095,42 +3138,116 @@ HookAPI::get_stobject_length(
                 return Unexpected(pe_unexpected_end);
         }
     }
-    else if ((type >= 1 && type <= 5) || type == 16 || type == 17)
+    else if (
+        (type >= STI_UINT16 && type <= STI_UINT256) || type == STI_UINT8 ||
+        type == STI_UINT160 || type == STI_CURRENCY)
     {
         switch (type)
         {
-            case SerializedTypeID::STI_UINT16:
+            case STI_UINT16:
                 length = 2;
                 break;
-            case SerializedTypeID::STI_UINT32:
+            case STI_UINT32:
                 length = 4;
                 break;
-            case SerializedTypeID::STI_UINT64:
+            case STI_UINT64:
                 length = 8;
                 break;
-            case SerializedTypeID::STI_UINT128:
+            case STI_UINT128:
                 length = 16;
                 break;
-            case SerializedTypeID::STI_UINT256:
+            case STI_UINT256:
                 length = 32;
                 break;
-            case SerializedTypeID::STI_UINT8:
+            case STI_UINT8:
                 length = 1;
                 break;
-            case SerializedTypeID::STI_UINT160:
+            case STI_UINT160:
+                length = 20;
+                break;
+            case STI_CURRENCY:
                 length = 20;
                 break;
             default:
-                length = -1;
-                break;
+                return -1;
         }
     }
-    else if (type == SerializedTypeID::STI_AMOUNT)
+    else if (type == STI_AMOUNT) /* AMOUNT */
     {
         length = (*upto >> 6 == 1) ? 8 : 48;
         if (upto >= end)
             return Unexpected(pe_unexpected_end);
     }
+    else if (
+        type == STI_PATHSET && rules.enabled(featureHookAPISerializedType240))
+    {
+        length = 0;
+        while (upto + length < end)
+        {
+            // iterate Path step
+            while (*(upto + length) & 0x01 || *(upto + length) & 0x10 ||
+                   *(upto + length) & 0x20)
+            {
+                int flag = *(upto + length++);
+                // flag shoud be 0x01 or 0x10 or 0x20 or those union
+                if (flag == 0 || flag & ~(0x01 | 0x10 | 0x20))
+                    return pe_unexpected_end;
+                if (flag & 0x01)  // account
+                    length += 20;
+                if (flag & 0x10)  // currency
+                    length += 20;
+                if (flag & 0x20)  // issuer
+                    length += 20;
+
+                int next_flag = *(upto + length);
+                if (next_flag == 0x00 || next_flag == 0xff)
+                    // end of Path step
+                    break;
+            }
+
+            // continue or end of Paths
+            int lastflag = *(upto + length++);
+            if (lastflag == 0xff)
+                continue;  // continue byte
+            else if (lastflag == 0x00)
+                break;  // end byte
+            else
+                return pe_unexpected_end;
+        }
+        if (upto >= end)
+            return pe_unexpected_end;
+    }
+    else if (type == STI_ISSUE)
+    {
+        auto zero20 = std::array<char, 20>{0};
+        // if first 20 byte is all zeros return 20
+        // else return 40
+        if (memcmp(upto, zero20.data(), 20) == 0)
+            length = 20;
+        else
+            length = 40;
+    }
+    else if (type == STI_XCHAIN_BRIDGE)
+    {
+        auto zero20 = std::array<char, 20>{0};
+        // Lock Chain
+        length = 1;    // Door Account1 prefix length
+        length += 20;  // Door Account1 length
+        // Door Issue1
+        if (memcmp(upto + length, zero20.data(), 20) == 0)
+            length += 20;  // only Currency
+        else
+            length += 40;  // Currency and Issue
+
+        // Issuing Chain
+        length += 1;   // Door Account2 prefix length
+        length += 20;  // Door Account2 length
+        // Door Issue2
+        if (memcmp(upto + length, zero20.data(), 20) == 0)
+            length += 20;  // only Currency
+        else
+            length += 40;  // Currency and Issue
+    }
 
     if (length > -1)
     {
@@ -3149,8 +3266,7 @@ HookAPI::get_stobject_length(
         return length + (upto - start);
     }
 
-    if (type == SerializedTypeID::STI_OBJECT ||
-        type == SerializedTypeID::STI_ARRAY)
+    if (type == STI_OBJECT || type == STI_ARRAY)
     {
         payload_start = upto - start;
 
@@ -3165,6 +3281,7 @@ HookAPI::get_stobject_length(
                 subfield,
                 payload_start_,
                 payload_length_,
+                hookCtx.applyCtx.view().rules(),
                 recursion_depth + 1);
             DBG_PRINTF(
                 "%d get_stobject_length i %d %d-%d, upto %d sublength %d\n",
@@ -3180,8 +3297,8 @@ HookAPI::get_stobject_length(
             if (upto >= end)
                 return Unexpected(pe_unexpected_end);
 
-            if ((*upto == 0xE1U && type == 0xEU) ||
-                (*upto == 0xF1U && type == 0xFU))
+            if ((*upto == 0xE1U && type == 0xEU) ||  // STI_OBJECT Maker
+                (*upto == 0xF1U && type == 0xFU))    // STI_ARRAY Maker
             {
                 payload_length = upto - start - payload_start;
                 upto++;