cve-2026-55962
MEDIUM CVSS 6.0 cvelistv5TLS 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.
- Published
- 2026-06-25 21:12 UTC
- Last Modified
- 2026-06-26
- Attack Vector
- NETWORK
- Attack Complexity
- LOW
- Privileges Required
- LOW
- wolfSSL wolfSSL
- Exploitation
none- Automatable
no- Technical Impact
partial- Decision timestamp
2026-06-26T10:30:28.816026Z
What is SSVC? — CISA's vulnerability-prioritisation framework using a decision tree rather than a single score.
No linked vulnerabilities found.
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