{"schema_version":"1.9.0","id":"CVE-2026-27448","published":"2026-03-17T23:24:30.661Z","modified":"2026-09-06T03:45:30.230958341Z","aliases":["GHSA-vp96-hxj8-p424","PYSEC-2026-2268"],"related":["CGA-855q-q8qp-fh5c","SUSE-EL-9-CLIENT-TOOLS-2026-2255","SUSE-RU-2026:2769-1","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","SUSE-SU-2026:21990-1","SUSE-SU-2026:2242-1","SUSE-SU-2026:2244-1","SUSE-SU-2026:2255-1","SUSE-SU-2026:3424-1","openSUSE-SU-2026:10392-1","openSUSE-SU-2026:20419-1"],"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.","affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/pyca/pyopenssl","events":[{"introduced":"0146d447e63a737b4f05a1164d5950eff68543e7"},{"fixed":"358cbf29c4e364c59930e53a270116249581eaa3"},{"fixed":"d41a814759a9fb49584ca8ab3f7295de49a85aa0"}],"database_specific":{"cpe":"cpe:2.3:a:pyopenssl:pyopenssl:*:*:*:*:*:*:*:*","extracted_events":[{"introduced":"0.14"},{"fixed":"26.0.0"}],"source":["CPE_RANGE","REFERENCES"]}}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-27448.json"}}],"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"}],"database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-636"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27448.json"},"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"}]}