CVE-2026-55962 - TLS 1.3 post-handshake authentication: server accepts Finished without client Certificate/CertificateVerify

CVE-2026-55962 - TLS 1.3 post-handshake authentication: server accepts Finished without client Certificate/CertificateVerify

https://cvefeed.io/rssfeed/latest.atom / Fri, 06/26/2026 - 01:01
CVE ID :CVE-2026-55962
Published : June 25, 2026, 9:12 p.m. | 1 hour, 29 minutes ago
Description :TLS 1.3 post-handshake authentication (PHA) issue where a server could accept a client's Finished message without the client having sent a Certificate and CertificateVerify. The post-handshake-auth exemption that allows an empty/absent peer certificate was only intended for the initial handshake, but it was also being applied while a post-handshake CertificateRequest was still outstanding. The check is now scoped to the initial handshake only: on the server, once a post-handshake CertificateRequest has been sent (certReqCtx is set), a peer certificate and a valid CertificateVerify are required again before the Finished is accepted, with empty-certificate handling following the configured verify mode (FAIL_IF_NO_PEER_CERT) just as during first-handshake client authentication. Only affects TLS 1.3 servers built with post-handshake authentication support (WOLFSSL_POST_HANDSHAKE_AUTH / --enable-postauth, included in --enable-all) that enable WOLFSSL_VERIFY_POST_HANDSHAKE and request a client certificate after the handshake via wolfSSL_request_certificate(). Clients, and servers that do not use post-handshake authentication, are unaffected.
Severity: 6.0 | MEDIUM
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