{"id":"GHSA-vp96-hxj8-p424","summary":"pyOpenSSL allows TLS connection bypass via unhandled callback exception in set_tlsext_servername_callback","details":"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.\n\nUnhandled exceptions now result in rejecting the connection.\n\nCredit to **Leury Castillo** for reporting this issue.","aliases":["CVE-2026-27448","PYSEC-2026-2268"],"modified":"2026-07-17T21:11:36.391070631Z","published":"2026-03-16T15:15:43Z","database_specific":{"severity":"LOW","github_reviewed":true,"github_reviewed_at":"2026-03-16T15:15:43Z","nvd_published_at":"2026-03-18T00:16:19Z","cwe_ids":["CWE-636"]},"references":[{"type":"WEB","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":"WEB","url":"https://github.com/pyca/pyopenssl/commit/d41a814759a9fb49584ca8ab3f7295de49a85aa0"},{"type":"PACKAGE","url":"https://github.com/pyca/pyopenssl"},{"type":"WEB","url":"https://github.com/pyca/pyopenssl/blob/358cbf29c4e364c59930e53a270116249581eaa3/CHANGELOG.rst#L27"}],"affected":[{"package":{"name":"pyopenssl","ecosystem":"PyPI","purl":"pkg:pypi/pyopenssl"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.14.0"},{"fixed":"26.0.0"}]}],"versions":["0.14","0.15","0.15.1","16.0.0","16.1.0","16.2.0","17.0.0","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","23.1.1","23.2.0","23.3.0","24.0.0","24.1.0","24.2.1","24.3.0","25.0.0","25.1.0","25.2.0","25.3.0"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-vp96-hxj8-p424/GHSA-vp96-hxj8-p424.json"}}],"schema_version":"1.9.0","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"}]}