CVE-2026-55962 (GCVE-0-2026-55962)

Vulnerability from cvelistv5 – Published: 2026-06-25 21:12 – Updated: 2026-06-26 10:31
VLAI?
Title
TLS 1.3 post-handshake authentication: server accepts Finished without client Certificate/CertificateVerify
Summary
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 (Medium)
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
CWE
  • CWE-287 - Improper Authentication
Assigner
References
Impacted products
Vendor Product Version
wolfSSL wolfSSL Affected: 5.5.4 , ≤ 5.9.1 (semver)
Create a notification for this product.
Credits
NVIDIA Project Vanessa
Show details on NVD website
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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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Detection rules are retrieved from Rulezet.