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F-6300 - Revert TLS 1.2 unsolicited ServerHello extension abort; breaks heartbeat interop

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aidan garske
2026-06-25 15:20:32 -07:00
parent 89bf094a5d
commit d53e3615a3
1 changed files with 18 additions and 20 deletions
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src/tls.c
+18 -20
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@@ -18578,31 +18578,29 @@ WOLFSSL_TEST_VIS int TLSX_Parse(WOLFSSL* ssl, const byte* input, word16 length,
#endif
default:
WOLFSSL_MSG("Unknown TLS extension type");
/* RFC 5246 Sec. 7.4.1.4 (TLS 1.2) and RFC 8446 Sec. 4.2
* (TLS 1.3): a client MUST abort with an unsupported_extension
* alert when it receives an extension "response" that was not
* advertised in the ClientHello. wolfSSL never offers an
* extension type that has no case here, so an unknown type in
* a ServerHello is always unsolicited.
*
* For TLS 1.3 the rule also covers HelloRetryRequest,
* EncryptedExtensions and Certificate. CertificateRequest and
* NewSessionTicket are independent server-initiated payloads,
* not responses, and per RFC 8701 (GREASE) the server MAY
* include unknown extension types there which the client MUST
* ignore like any other unknown value. */
if (msgType == server_hello
#if defined(WOLFSSL_TLS13)
|| (IsAtLeastTLSv1_3(ssl->version) &&
(msgType == hello_retry_request ||
msgType == encrypted_extensions ||
msgType == certificate))
#endif
) {
/* RFC 8446 Sec. 4.2: a TLS 1.3 client MUST abort with an
* unsupported_extension alert when it receives an extension
* "response" that was not advertised in the ClientHello. The
* rule applies only to messages whose extensions are responses
* to the ClientHello: ServerHello, HelloRetryRequest,
* EncryptedExtensions and Certificate.
*
* Extensions in CertificateRequest and NewSessionTicket are
* independent server-initiated payloads, not responses, and
* per RFC 8701 (GREASE) the server MAY include unknown
* (GREASE) extension types there which the client MUST treat
* like any other unknown value (i.e. ignore them). */
if (IsAtLeastTLSv1_3(ssl->version) &&
(msgType == server_hello ||
msgType == hello_retry_request ||
msgType == encrypted_extensions ||
msgType == certificate)) {
SendAlert((WOLFSSL*)ssl, alert_fatal, unsupported_extension);
WOLFSSL_ERROR_VERBOSE(UNSUPPORTED_EXTENSION);
return UNSUPPORTED_EXTENSION;
}
#endif
}
/* offset should be updated here! */