{"id":"CVE-2026-55962","aliases":["ALPINE-CVE-2026-55962","DEBIAN-CVE-2026-55962","EUVD-2026-39575","GHSA-gq94-hf88-g4wv","JLSEC-2026-737","UBUNTU-CVE-2026-55962"],"status":"published","title":"TLS 1.3 post-handshake authentication: server accepts Finished without client Certificate/CertificateVerify","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":{"version":"4.0","score":6,"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","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-09","score":0.00235,"percentile":0.14503,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-287"],"published":"2026-06-25T21:12:38Z","modified":"2026-11-03T06:33:05Z","fixes":[{"ecosystem":"Alpine:v3.24","package":"wolfssl","fixed_in":["5.9.2-r0"],"sources":["osv"]},{"ecosystem":"Debian:12","package":"wolfssl","fixed_in":["5.5.4-2+deb12u3"],"sources":["osv"]},{"ecosystem":"Debian:13","package":"wolfssl","fixed_in":["5.7.2-0.1+deb13u2"],"sources":["osv"]},{"ecosystem":"Julia","package":"wolfSSL_jll","fixed_in":["5.9.2+0"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Alpine:v3.24","package":"wolfssl","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.5.4"},{"fixed":"5.9.2-r0"}]}]},{"source":"osv","ecosystem":"Debian:12","package":"wolfssl","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.5.4-2+deb12u3"}]}],"versions":["5.5.4-2","5.5.4-2+deb12u1","5.5.4-2+deb12u2"]},{"source":"osv","ecosystem":"Debian:13","package":"wolfssl","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.7.2-0.1+deb13u2"}]}],"versions":["5.7.2-0.1","5.7.2-0.1+deb13u1"]},{"source":"osv","ecosystem":"Julia","package":"wolfSSL_jll","ranges":[{"type":"SEMVER","events":[{"introduced":"5.7.2+0"},{"fixed":"5.9.2+0"}]}]},{"source":"osv","ecosystem":"Ubuntu:16.04:LTS","package":"wolfssl","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.4.8+dfsg-1"]},{"source":"osv","ecosystem":"Ubuntu:18.04:LTS","package":"wolfssl","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.10.2+dfsg-2","3.12.0+dfsg-1","3.12.2+dfsg-1","3.13.0+dfsg-1"]},{"source":"osv","ecosystem":"Ubuntu:20.04:LTS","package":"wolfssl","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.1.0+dfsg-2","4.2.0+dfsg-1","4.2.0+dfsg-2","4.2.0+dfsg-3","4.3.0+dfsg-2"]},{"source":"osv","ecosystem":"Ubuntu:22.04:LTS","package":"wolfssl","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["4.6.0-3","5.0.0-1","5.1.1-1","5.2.0-1","5.2.0-2"]},{"source":"osv","ecosystem":"Ubuntu:24.04:LTS","package":"wolfssl","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["5.5.4-2","5.5.4-2.1","5.6.4-2","5.6.6-1.2","5.6.6-1.3","5.6.6-1.3build1"]},{"source":"osv","ecosystem":"Ubuntu:25.10","package":"wolfssl","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["5.7.2-0.1"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"wolfssl","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["5.9.1-0.1","5.9.2-1"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"wolfssl","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["5.7.2-0.1","5.8.2-1.2","5.8.4-1","5.9.1-0.1"]}],"products":[{"vendor":"wolfssl","product":"wolfssl"}],"references":[{"url":"https://github.com/wolfSSL/wolfssl/pull/10702","tags":["patch","Issue Tracking","Patch","fix","web","report"]},{"url":"https://www.wolfssl.com/docs/security-vulnerabilities/","tags":["Vendor Advisory","web","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-55962","tags":["advisory","web"]},{"url":"https://www.wolfssl.com/docs/security-vulnerabilities","tags":["web"]},{"url":"https://github.com/advisories/GHSA-gq94-hf88-g4wv","tags":["web"]},{"url":"https://security.alpinelinux.org/vuln/CVE-2026-55962","tags":["advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55962.json","tags":["advisory"]},{"url":"https://github.com/wolfSSL/wolfssl","tags":["package"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-55962","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2026-55962","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-55962","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2026-55962","title":"TLS 1.3 post-handshake authentication: server accepts Finished without client Certificate/CertificateVerify","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.","status":"published","published":"2026-06-25T21:12:38.074Z","modified":"2026-06-26T10:31:12.017Z","cvss":[{"version":"4.0","score":6,"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","level":"medium","assessor":"cna"}],"cwes":["CWE-287"],"updated_at":"2026-11-02T14:20:12.260247Z"}],"euvd":[{"id":"EUVD-2026-39575","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.","status":"published","published":"2026-06-25T21:12:38Z","modified":"2026-06-26T10:31:12Z","cvss":[{"version":"4.0","score":6,"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","level":"medium"}],"updated_at":"2026-11-02T18:20:24.957062Z"}],"ghsa":[{"id":"GHSA-gq94-hf88-g4wv","title":"TLS 1.3 post-handshake authentication (PHA) issue where a server could accept a client's Finished...","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.","status":"published","published":"2026-06-26T00:32:06Z","modified":"2026-06-27T21:31:34Z","cvss":[{"version":"4.0","score":6,"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"medium"},{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N","level":"medium"}],"cwes":["CWE-287"],"updated_at":"2026-11-02T15:09:02.633671Z"}],"nvd":[{"id":"CVE-2026-55962","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.","status":"published","published":"2026-06-25T22:17:02.26Z","modified":"2026-06-27T19:57:59.51Z","cvss":[{"version":"4.0","score":6,"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"medium","assessor":"secondary"},{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N","level":"medium","assessor":"primary"}],"cwes":["CWE-287"],"updated_at":"2026-11-02T14:12:26.045561Z"}],"osv":[{"id":"ALPINE-CVE-2026-55962","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.","status":"published","published":"2026-06-25T22:17:02.26Z","modified":"2026-11-03T06:33:05.803322639Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N","level":"medium"}],"updated_at":"2026-11-03T07:15:37.282377Z"},{"id":"CVE-2026-55962","title":"TLS 1.3 post-handshake authentication: server accepts Finished without client Certificate/CertificateVerify","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.","status":"published","published":"2026-06-25T21:12:38.074Z","modified":"2026-10-28T02:30:47.250338373Z","cvss":[{"version":"4.0","score":6,"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","level":"medium"}],"cwes":["CWE-287"],"updated_at":"2026-11-02T15:45:11.609219Z"},{"id":"DEBIAN-CVE-2026-55962","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.","status":"published","published":"2026-06-25T22:17:02.26Z","modified":"2026-10-01T03:03:26.801942853Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N","level":"medium"}],"updated_at":"2026-11-02T15:45:57.590991Z"},{"id":"JLSEC-2026-737","title":"TLS 1.3 post-handshake authentication (PHA) issue where a server could accept a client's Finished...","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.","status":"published","published":"2026-07-14T21:41:35.775Z","modified":"2026-07-25T18:24:01.000290377Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N","level":"medium"},{"version":"4.0","score":6,"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"medium"}],"updated_at":"2026-11-02T15:47:19.003546Z"},{"id":"UBUNTU-CVE-2026-55962","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.","status":"published","published":"2026-06-25T22:17:00Z","modified":"2026-10-17T13:00:27.258082661Z","cvss":[{"version":"4.0","score":6,"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","level":"medium"},{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N","level":"medium"}],"updated_at":"2026-11-02T16:56:41.382716Z"}]}}