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

{
    "lastseen": "",
    "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.",
    "published": "2026-06-25T21:12:38.074Z",
    "modified": "2026-06-25T21:12:38.074Z",
    "type": "cve",
    "title": "TLS 1.3 post-handshake authentication: server accepts Finished without client Certificate/CertificateVerify",
    "source": "wolfSSL",
    "references": "https://github.com/wolfSSL/wolfssl/pull/10702\nhttps://www.wolfssl.com/docs/security-vulnerabilities/",
    "id": "CVE-2026-55962",
    "bulletinFamily": "",
    "cwe": [
        "CWE-287"
    ],
    "cvelist": null,
    "sourceData": "wolfSSL wolfSSL 5.5.4",
    "sourceHref": "",
    "cvss": {
        "score": 6,
        "severity": "MEDIUM",
        "vector": "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",
        "version": "4.0"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
            "userInteraction": "",
            "scope": "",
            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "wolfSSL",
    "version": "5.5.4",
    "vendor": "wolfSSL",
    "ai_description": "",
    "ai_severity": "",
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    "ai_score": 0
}