diff --git a/src/internal.c b/src/internal.c
index af7a695f41..ce1dc8e2b8 100644
--- a/src/internal.c
+++ b/src/internal.c
@@ -8669,6 +8669,9 @@ void FreeKeyExchange(WOLFSSL* ssl)
 {
     /* Cleanup signature buffer */
     if (ssl->buffers.sig.buffer) {
+        /* May transiently hold the client's DH private exponent in the
+         * TLS 1.2 diffie_hellman_kea / dhe_psk_kea paths. */
+        ForceZero(ssl->buffers.sig.buffer, ssl->buffers.sig.length);
         XFREE(ssl->buffers.sig.buffer, ssl->heap, DYNAMIC_TYPE_SIGNATURE);
         ssl->buffers.sig.buffer = NULL;
         ssl->buffers.sig.length = 0;
diff --git a/src/pk.c b/src/pk.c
index e4cfe897d9..8b0dbe705d 100644
--- a/src/pk.c
+++ b/src/pk.c
@@ -4743,6 +4743,7 @@ int wolfSSL_DH_generate_key(WOLFSSL_DH* dh)
     int     ret    = 1;
     word32  pubSz  = 0;
     word32  privSz = 0;
+    word32  privAllocSz = 0;
     int     localRng = 0;
     WC_RNG* rng    = NULL;
     WC_DECLARE_VAR(tmpRng, WC_RNG, 1, 0);
@@ -4792,9 +4793,12 @@ int wolfSSL_DH_generate_key(WOLFSSL_DH* dh)
         else {
             privSz = pubSz;
         }
-        /* Allocate public and private key arrays. */
+        /* Allocate public and private key arrays. Preserve the allocation
+         * size because wc_DhGenerateKeyPair updates privSz in-place. */
+        privAllocSz = privSz;
         pub = (unsigned char*)XMALLOC(pubSz, NULL, DYNAMIC_TYPE_PUBLIC_KEY);
-        priv = (unsigned char*)XMALLOC(privSz, NULL, DYNAMIC_TYPE_PRIVATE_KEY);
+        priv = (unsigned char*)XMALLOC(privAllocSz, NULL,
+            DYNAMIC_TYPE_PRIVATE_KEY);
         if (pub == NULL || priv == NULL) {
             WOLFSSL_ERROR_MSG("Unable to malloc memory");
             ret = 0;
@@ -4846,7 +4850,10 @@ int wolfSSL_DH_generate_key(WOLFSSL_DH* dh)
     }
     /* Dispose of allocated data. */
     XFREE(pub,  NULL, DYNAMIC_TYPE_PUBLIC_KEY);
-    XFREE(priv, NULL, DYNAMIC_TYPE_PRIVATE_KEY);
+    if (priv != NULL) {
+        ForceZero(priv, privAllocSz);
+        XFREE(priv, NULL, DYNAMIC_TYPE_PRIVATE_KEY);
+    }
 
     return ret;
 }
diff --git a/src/sniffer.c b/src/sniffer.c
index f46da14654..8218131435 100644
--- a/src/sniffer.c
+++ b/src/sniffer.c
@@ -2459,11 +2459,15 @@ static void FreeSetupKeysArgs(WOLFSSL* ssl, void* pArgs)
         args->key->type = WC_PK_TYPE_NONE;
         args->key->initPriv = 0; args->key->initPub = 0;
 
+        /* Scrub the raw DH private exponent (and any other key material
+         * embedded in the union) before release. wc_FreeDhKey above only
+         * clears the mp_int DhKey, not the separate privKey byte array.
+         * Use ForceZero (rather than XMEMSET) so the wipe cannot be
+         * elided by the optimizer. */
+        ForceZero(args->key, sizeof(*args->key));
 #ifdef WOLFSSL_ASYNC_CRYPT
         XFREE(args->key, NULL, DYNAMIC_TYPE_SNIFFER_KEY);
         args->key = NULL;
-#else
-        XMEMSET(args->key, 0, sizeof(args->key));
 #endif
     }
 
diff --git a/src/ssl.c b/src/ssl.c
index bc7e6074c8..b3cd4beb1f 100644
--- a/src/ssl.c
+++ b/src/ssl.c
@@ -10069,11 +10069,21 @@ size_t wolfSSL_get_client_random(const WOLFSSL* ssl, unsigned char* out,
     #ifdef WOLFSSL_DTLS
         ssl->options.dtlsStateful = 0;
     #endif
+    #ifdef WOLFSSL_TLS13
     #if defined(HAVE_SESSION_TICKET) || !defined(NO_PSK)
-        ssl->options.noPskDheKe = 0;
-      #ifdef HAVE_SUPPORTED_CURVES
-        ssl->options.onlyPskDheKe = 0;
-      #endif
+        if (ssl->ctx != NULL) {
+            ssl->options.noPskDheKe = ssl->ctx->noPskDheKe;
+          #ifdef HAVE_SUPPORTED_CURVES
+            ssl->options.onlyPskDheKe = ssl->ctx->onlyPskDheKe;
+          #endif
+        }
+        else {
+            ssl->options.noPskDheKe = 0;
+          #ifdef HAVE_SUPPORTED_CURVES
+            ssl->options.onlyPskDheKe = 0;
+          #endif
+        }
+    #endif
     #endif
     #ifdef HAVE_SESSION_TICKET
         #ifdef WOLFSSL_TLS13
diff --git a/src/ssl_crypto.c b/src/ssl_crypto.c
index c5cee713ef..81f17c8dda 100644
--- a/src/ssl_crypto.c
+++ b/src/ssl_crypto.c
@@ -2722,11 +2722,19 @@ void wolfSSL_DES_ncbc_encrypt(const unsigned char* input, unsigned char* output,
     int enc)
 {
     unsigned char tmp[DES_IV_SIZE];
-    /* Calculate length to a multiple of block size. */
-    size_t offset = (size_t)length;
+    size_t offset;
 
     WOLFSSL_ENTER("wolfSSL_DES_ncbc_encrypt");
 
+    /* Zero/negative length: no block to derive an IV from. The offset math
+     * below would underflow for length == 0, yielding a wild-pointer read. */
+    if (length <= 0) {
+        WOLFSSL_LEAVE("wolfSSL_DES_ncbc_encrypt", 0);
+        return;
+    }
+
+    /* Calculate length to a multiple of block size. */
+    offset = (size_t)length;
     offset = (offset + DES_BLOCK_SIZE - 1) / DES_BLOCK_SIZE;
     offset *= DES_BLOCK_SIZE;
     offset -= DES_BLOCK_SIZE;
diff --git a/src/ssl_load.c b/src/ssl_load.c
index 2841f22e8e..cada9e7560 100644
--- a/src/ssl_load.c
+++ b/src/ssl_load.c
@@ -5513,10 +5513,13 @@ int wolfSSL_CTX_set_default_verify_paths(WOLFSSL_CTX* ctx)
             ret = 1;
         }
     #else
-        /* OpenSSL's implementation of this API does not require loading the
-         * system CA cert directory.  Allow skipping this without erroring out.
-         */
-        ret = 1;
+        /* No source available: SSL_CERT_DIR/SSL_CERT_FILE not set and
+         * WOLFSSL_SYS_CA_CERTS not compiled in. Returning success would be
+         * fail-open since no trust anchors were loaded. */
+        WOLFSSL_MSG("wolfSSL_CTX_set_default_verify_paths: no CA source "
+                    "available (build without WOLFSSL_SYS_CA_CERTS and no "
+                    "SSL_CERT_DIR/SSL_CERT_FILE env)");
+        ret = WOLFSSL_FAILURE;
     #endif
     }
 
diff --git a/src/ssl_sess.c b/src/ssl_sess.c
index d1d4acf20d..d849c35000 100644
--- a/src/ssl_sess.c
+++ b/src/ssl_sess.c
@@ -1598,8 +1598,12 @@ int wolfSSL_SetSession(WOLFSSL* ssl, WOLFSSL_SESSION* session)
 #if !defined(OPENSSL_EXTRA) || !defined(WOLFSSL_ERROR_CODE_OPENSSL)
         return WOLFSSL_FAILURE;  /* session timed out */
 #else /* defined(OPENSSL_EXTRA) && defined(WOLFSSL_ERROR_CODE_OPENSSL) */
+        /* Return success for OpenSSL compatibility but do not carry the
+         * expired session's version/cipher into ssl state, which would
+         * otherwise pin the ClientHello to stale values. */
         WOLFSSL_MSG("Session is expired but return success for "
                     "OpenSSL compatibility");
+        return WOLFSSL_SUCCESS;
 #endif
     }
     ssl->options.resuming = 1;
diff --git a/src/tls.c b/src/tls.c
index 347761b263..5b87bb2a29 100644
--- a/src/tls.c
+++ b/src/tls.c
@@ -9063,6 +9063,9 @@ static void TLSX_KeyShare_FreeAll(KeyShareEntry* list, void* heap)
         if (WOLFSSL_NAMED_GROUP_IS_FFDHE(current->group)) {
 #ifndef NO_DH
             wc_FreeDhKey((DhKey*)current->key);
+            if (current->privKey != NULL && current->privKeyLen > 0) {
+                ForceZero(current->privKey, current->privKeyLen);
+            }
 #endif
         }
         else if (current->group == WOLFSSL_ECC_X25519) {
@@ -17208,8 +17211,8 @@ static word16 TLSX_GetMinSize_Server(const word16 *type)
 
 
 /** Parses a buffer of TLS extensions. */
-int TLSX_Parse(WOLFSSL* ssl, const byte* input, word16 length, byte msgType,
-                                                                 Suites *suites)
+WOLFSSL_TEST_VIS int TLSX_Parse(WOLFSSL* ssl, const byte* input, word16 length,
+                                byte msgType, Suites *suites)
 {
     int ret = 0;
     word16 offset = 0;
@@ -17831,6 +17834,20 @@ int TLSX_Parse(WOLFSSL* ssl, const byte* input, word16 length, byte msgType,
 #ifdef WOLFSSL_SRTP
             case TLSX_USE_SRTP:
                 WOLFSSL_MSG("Use SRTP extension received");
+
+#if defined(WOLFSSL_TLS13)
+                if (IsAtLeastTLSv1_3(ssl->version)) {
+                    if (msgType != client_hello &&
+                        msgType != encrypted_extensions)
+                        return EXT_NOT_ALLOWED;
+                }
+                else
+#endif
+                {
+                    if (msgType != client_hello &&
+                        msgType != server_hello)
+                        return EXT_NOT_ALLOWED;
+                }
                 ret = SRTP_PARSE(ssl, input + offset, size, isRequest);
                 break;
 #endif
@@ -17925,6 +17942,15 @@ int TLSX_Parse(WOLFSSL* ssl, const byte* input, word16 length, byte msgType,
 #if defined(WOLFSSL_TLS13) && defined(HAVE_ECH)
             case TLSX_ECH:
                 WOLFSSL_MSG("ECH extension received");
+                if (!IsAtLeastTLSv1_3(ssl->version))
+                    break;
+
+                if (msgType != client_hello &&
+                    msgType != encrypted_extensions &&
+                    msgType != hello_retry_request) {
+                    return EXT_NOT_ALLOWED;
+                }
+
                 ret = ECH_PARSE(ssl, input + offset, size, msgType);
                 break;
             case TLSXT_ECH_OUTER_EXTENSIONS:
diff --git a/tests/api.c b/tests/api.c
index 389cf8e518..c12f7dbfc8 100644
--- a/tests/api.c
+++ b/tests/api.c
@@ -39692,6 +39692,8 @@ TEST_CASE testCases[] = {
     TEST_DECL(test_certificate_authorities_client_hello),
     TEST_DECL(test_TLSX_TCA_Find),
     TEST_DECL(test_TLSX_SNI_GetSize_overflow),
+    TEST_DECL(test_TLSX_ECH_msg_type_validation),
+    TEST_DECL(test_TLSX_SRTP_msg_type_validation),
     TEST_DECL(test_wolfSSL_wolfSSL_UseSecureRenegotiation),
     TEST_DECL(test_wolfSSL_clear_secure_renegotiation),
     TEST_DECL(test_wolfSSL_SCR_Reconnect),
diff --git a/tests/api/test_ossl_cipher.c b/tests/api/test_ossl_cipher.c
index 096a352ce5..f40b097546 100644
--- a/tests/api/test_ossl_cipher.c
+++ b/tests/api/test_ossl_cipher.c
@@ -203,6 +203,34 @@ int test_wolfSSL_DES_ncbc(void)
     return EXPECT_RESULT();
 }
 
+int test_wolfSSL_DES_ncbc_zero_length(void)
+{
+    EXPECT_DECLS;
+#if defined(OPENSSL_EXTRA) && !defined(NO_DES3)
+    const_DES_cblock myDes;
+    DES_cblock iv;
+    DES_cblock ivSaved;
+    DES_key_schedule key = {0};
+    unsigned char msg[DES_BLOCK_SIZE] = {0};
+    unsigned char out[DES_BLOCK_SIZE] = {0};
+
+    DES_set_key(&key, &myDes);
+
+    /* length == 0 must no-op: the offset math would otherwise underflow
+     * size_t and read from a wild pointer. */
+    XMEMSET((byte*)&iv, 0xAB, DES_BLOCK_SIZE);
+    XMEMCPY(&ivSaved, &iv, DES_BLOCK_SIZE);
+    DES_ncbc_encrypt(msg, out, 0, &myDes, &iv, DES_ENCRYPT);
+    ExpectIntEQ(XMEMCMP(&iv, &ivSaved, DES_BLOCK_SIZE), 0);
+
+    XMEMSET((byte*)&iv, 0xAB, DES_BLOCK_SIZE);
+    XMEMCPY(&ivSaved, &iv, DES_BLOCK_SIZE);
+    DES_ncbc_encrypt(msg, out, 0, &myDes, &iv, DES_DECRYPT);
+    ExpectIntEQ(XMEMCMP(&iv, &ivSaved, DES_BLOCK_SIZE), 0);
+#endif
+    return EXPECT_RESULT();
+}
+
 int test_wolfSSL_DES_ecb_encrypt(void)
 {
     EXPECT_DECLS;
diff --git a/tests/api/test_ossl_cipher.h b/tests/api/test_ossl_cipher.h
index caa49928b4..a57657d0c5 100644
--- a/tests/api/test_ossl_cipher.h
+++ b/tests/api/test_ossl_cipher.h
@@ -26,6 +26,7 @@
 
 int test_wolfSSL_DES(void);
 int test_wolfSSL_DES_ncbc(void);
+int test_wolfSSL_DES_ncbc_zero_length(void);
 int test_wolfSSL_DES_ecb_encrypt(void);
 int test_wolfSSL_DES_ede3_cbc_encrypt(void);
 int test_wolfSSL_AES_encrypt(void);
@@ -38,6 +39,7 @@ int test_wolfSSL_RC4(void);
 #define TEST_OSSL_CIPHER_DECLS                                          \
     TEST_DECL_GROUP("ossl_cipher", test_wolfSSL_DES),                   \
     TEST_DECL_GROUP("ossl_cipher", test_wolfSSL_DES_ncbc),              \
+    TEST_DECL_GROUP("ossl_cipher", test_wolfSSL_DES_ncbc_zero_length),  \
     TEST_DECL_GROUP("ossl_cipher", test_wolfSSL_DES_ecb_encrypt),       \
     TEST_DECL_GROUP("ossl_cipher", test_wolfSSL_DES_ede3_cbc_encrypt),  \
     TEST_DECL_GROUP("ossl_cipher", test_wolfSSL_AES_encrypt),           \
diff --git a/tests/api/test_tls13.c b/tests/api/test_tls13.c
index 81872bc985..c66ffca698 100644
--- a/tests/api/test_tls13.c
+++ b/tests/api/test_tls13.c
@@ -5732,3 +5732,29 @@ int test_tls13_serverhello_bad_cipher_suites(void)
 #endif
     return EXPECT_RESULT();
 }
+
+int test_tls13_clear_preserves_psk_dhe(void)
+{
+    EXPECT_DECLS;
+#if (defined(OPENSSL_EXTRA) || defined(WOLFSSL_WPAS_SMALL)) && \
+    defined(WOLFSSL_TLS13) && defined(HAVE_SUPPORTED_CURVES) && \
+    (defined(HAVE_SESSION_TICKET) || !defined(NO_PSK)) && \
+    !defined(NO_WOLFSSL_CLIENT)
+    WOLFSSL_CTX* ctx = NULL;
+    WOLFSSL* ssl = NULL;
+
+    ExpectNotNull(ctx = wolfSSL_CTX_new(wolfTLSv1_3_client_method()));
+    ExpectIntEQ(wolfSSL_CTX_no_dhe_psk(ctx), 0);
+    ExpectNotNull(ssl = wolfSSL_new(ctx));
+    ExpectIntEQ(ssl->options.noPskDheKe, 1);
+
+    /* SSL reuse must preserve the CTX-level noPskDheKe; resetting to 0
+     * would silently re-enable psk_dhe_ke for the next handshake. */
+    ExpectIntEQ(wolfSSL_clear(ssl), WOLFSSL_SUCCESS);
+    ExpectIntEQ(ssl->options.noPskDheKe, 1);
+
+    wolfSSL_free(ssl);
+    wolfSSL_CTX_free(ctx);
+#endif
+    return EXPECT_RESULT();
+}
diff --git a/tests/api/test_tls13.h b/tests/api/test_tls13.h
index d508465e9a..ddd796edb3 100644
--- a/tests/api/test_tls13.h
+++ b/tests/api/test_tls13.h
@@ -66,6 +66,7 @@ int test_tls13_cert_with_extern_psk_requires_key_share(void);
 int test_tls13_cert_with_extern_psk_rejects_resumption(void);
 int test_tls13_cert_with_extern_psk_sh_missing_key_share(void);
 int test_tls13_cert_with_extern_psk_sh_confirms_resumption(void);
+int test_tls13_clear_preserves_psk_dhe(void);
 
 #define TEST_TLS13_DECLS                                        \
     TEST_DECL_GROUP("tls13", test_tls13_apis),                  \
@@ -109,6 +110,7 @@ int test_tls13_cert_with_extern_psk_sh_confirms_resumption(void);
     TEST_DECL_GROUP("tls13", test_tls13_cert_with_extern_psk_requires_key_share), \
     TEST_DECL_GROUP("tls13", test_tls13_cert_with_extern_psk_rejects_resumption), \
     TEST_DECL_GROUP("tls13", test_tls13_cert_with_extern_psk_sh_missing_key_share), \
-    TEST_DECL_GROUP("tls13", test_tls13_cert_with_extern_psk_sh_confirms_resumption)
+    TEST_DECL_GROUP("tls13", test_tls13_cert_with_extern_psk_sh_confirms_resumption), \
+    TEST_DECL_GROUP("tls13", test_tls13_clear_preserves_psk_dhe)
 
 #endif /* WOLFCRYPT_TEST_TLS13_H */
diff --git a/tests/api/test_tls_ext.c b/tests/api/test_tls_ext.c
index d183bfe6db..294fa9c903 100644
--- a/tests/api/test_tls_ext.c
+++ b/tests/api/test_tls_ext.c
@@ -982,3 +982,54 @@ int test_TLSX_SNI_GetSize_overflow(void)
 #endif
     return EXPECT_RESULT();
 }
+
+/* ECH is only valid in ClientHello, EncryptedExtensions, or
+ * HelloRetryRequest per RFC 9460. Feeding it in a Finished message must
+ * be rejected with EXT_NOT_ALLOWED rather than being silently accepted. */
+int test_TLSX_ECH_msg_type_validation(void)
+{
+    EXPECT_DECLS;
+#if defined(WOLFSSL_TLS13) && defined(HAVE_ECH) && \
+    !defined(NO_WOLFSSL_CLIENT) && !defined(NO_TLS)
+    WOLFSSL_CTX* ctx = NULL;
+    WOLFSSL* ssl = NULL;
+    /* type = TLSX_ECH (0xfe0d), size = 0x0000 */
+    const byte extBytes[] = { 0xfe, 0x0d, 0x00, 0x00 };
+
+    ExpectNotNull(ctx = wolfSSL_CTX_new(wolfTLSv1_3_client_method()));
+    ExpectNotNull(ssl = wolfSSL_new(ctx));
+
+    ExpectIntEQ(TLSX_Parse(ssl, extBytes, (word16)sizeof(extBytes),
+                           finished, NULL),
+                WC_NO_ERR_TRACE(EXT_NOT_ALLOWED));
+
+    wolfSSL_free(ssl);
+    wolfSSL_CTX_free(ctx);
+#endif
+    return EXPECT_RESULT();
+}
+
+/* use_srtp is only valid in ClientHello/ServerHello (pre-TLS 1.3) or
+ * ClientHello/EncryptedExtensions (TLS 1.3) per RFC 5764. Feeding it in a
+ * Finished message must be rejected with EXT_NOT_ALLOWED. */
+int test_TLSX_SRTP_msg_type_validation(void)
+{
+    EXPECT_DECLS;
+#if defined(WOLFSSL_SRTP) && !defined(NO_WOLFSSL_CLIENT) && !defined(NO_TLS)
+    WOLFSSL_CTX* ctx = NULL;
+    WOLFSSL* ssl = NULL;
+    /* type = TLSX_USE_SRTP (0x000e), size = 0x0000 */
+    const byte extBytes[] = { 0x00, 0x0e, 0x00, 0x00 };
+
+    ExpectNotNull(ctx = wolfSSL_CTX_new(wolfSSLv23_client_method()));
+    ExpectNotNull(ssl = wolfSSL_new(ctx));
+
+    ExpectIntEQ(TLSX_Parse(ssl, extBytes, (word16)sizeof(extBytes),
+                           finished, NULL),
+                WC_NO_ERR_TRACE(EXT_NOT_ALLOWED));
+
+    wolfSSL_free(ssl);
+    wolfSSL_CTX_free(ctx);
+#endif
+    return EXPECT_RESULT();
+}
diff --git a/tests/api/test_tls_ext.h b/tests/api/test_tls_ext.h
index 7d0921c9ad..e9d07d81ec 100644
--- a/tests/api/test_tls_ext.h
+++ b/tests/api/test_tls_ext.h
@@ -34,5 +34,7 @@ int test_certificate_authorities_certificate_request(void);
 int test_certificate_authorities_client_hello(void);
 int test_TLSX_TCA_Find(void);
 int test_TLSX_SNI_GetSize_overflow(void);
+int test_TLSX_ECH_msg_type_validation(void);
+int test_TLSX_SRTP_msg_type_validation(void);
 
 #endif /* TESTS_API_TEST_TLS_EMS_H */
diff --git a/wolfssl/internal.h b/wolfssl/internal.h
index f48de685cc..e62e98916b 100644
--- a/wolfssl/internal.h
+++ b/wolfssl/internal.h
@@ -3231,7 +3231,10 @@ WOLFSSL_LOCAL int   TLSX_ParseVersion(WOLFSSL* ssl, const byte* input,
 WOLFSSL_LOCAL int TLSX_SupportedVersions_Parse(const WOLFSSL* ssl,
         const byte* input, word16 length, byte msgType, ProtocolVersion* pv,
         Options* opts, TLSX** exts);
-WOLFSSL_LOCAL int   TLSX_Parse(WOLFSSL* ssl, const byte* input, word16 length,
+#ifdef WOLFSSL_API_PREFIX_MAP
+    #define TLSX_Parse wolfSSL_TLSX_Parse
+#endif
+WOLFSSL_TEST_VIS int TLSX_Parse(WOLFSSL* ssl, const byte* input, word16 length,
                                byte msgType, Suites *suites);
 WOLFSSL_LOCAL int TLSX_Push(TLSX** list, TLSX_Type type,
                             const void* data, void* heap);