{"id":"CVE-2026-27448","summary":"pyOpenSSL allows TLS connection bypass via unhandled callback exception in set_tlsext_servername_callback","details":"pyOpenSSL is a Python wrapper around the OpenSSL library. Starting in version 0.14.0 and prior to version 26.0.0, if a user provided callback to `set_tlsext_servername_callback` raised an unhandled exception, this would result in a connection being accepted. If a user was relying on this callback for any security-sensitive behavior, this could allow bypassing it. Starting in version 26.0.0, unhandled exceptions now result in rejecting the connection.","aliases":["GHSA-vp96-hxj8-p424"],"modified":"2026-04-25T07:59:21.410407126Z","published":"2026-03-17T23:24:30.661Z","related":["CGA-855q-q8qp-fh5c","SUSE-SU-2026:1192-1","SUSE-SU-2026:1416-1","SUSE-SU-2026:1582-1","SUSE-SU-2026:20930-1","SUSE-SU-2026:20954-1","SUSE-SU-2026:20960-1","openSUSE-SU-2026:10392-1","openSUSE-SU-2026:20419-1"],"database_specific":{"cwe_ids":["CWE-636"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27448.json","cna_assigner":"GitHub_M"},"references":[{"type":"WEB","url":"https://github.com/pyca/pyopenssl/blob/358cbf29c4e364c59930e53a270116249581eaa3/CHANGELOG.rst#L27"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27448.json"},{"type":"ADVISORY","url":"https://github.com/pyca/pyopenssl/security/advisories/GHSA-vp96-hxj8-p424"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-27448"},{"type":"FIX","url":"https://github.com/pyca/pyopenssl/commit/d41a814759a9fb49584ca8ab3f7295de49a85aa0"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/pyca/pyopenssl","events":[{"introduced":"0"},{"fixed":"358cbf29c4e364c59930e53a270116249581eaa3"}]}],"versions":["0.15","0.15.1","16.0.0","16.1.0","16.2.0","17.1.0","17.2.0","17.3.0","17.4.0","17.5.0","18.0.0","19.0.0","19.1.0","20.0.0","20.0.1","21.0.0","22.0.0","22.1.0","23.0.0","23.1.0","23.2.0","23.3.0","24.0.0","24.1.0","24.2.0","24.2.1","24.3.0","25.0.0","25.1.0","25.2.0","25.3.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-27448.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U"}]}