{"cve":"CVE-2026-27448","nvd":{"published":"2026-03-18T00:16:19.107","modified":"2026-06-17T10:27:10.570","status":"Analyzed","description":"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.","cvss_v4":{"vector":"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","score":1.7},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","score":5.3},"cwes":["CWE-636"],"references":["https://github.com/pyca/pyopenssl/blob/358cbf29c4e364c59930e53a270116249581eaa3/CHANGELOG.rst#L27","https://github.com/pyca/pyopenssl/commit/d41a814759a9fb49584ca8ab3f7295de49a85aa0","https://github.com/pyca/pyopenssl/security/advisories/GHSA-vp96-hxj8-p424"],"products":["pyopenssl:pyopenssl"],"source":"nvd","synced_at":"2026-10-19T22:26:19.218427112+00:00"},"epss":{"cve":"CVE-2026-27448","score":0.00251,"percentile":0.16475,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-vp96-hxj8-p424","url":"https://osv.dev/vulnerability/GHSA-vp96-hxj8-p424","summary":"pyOpenSSL allows TLS connection bypass via unhandled callback exception in set_tlsext_servername_callback","modified":"2026-09-10T03:51:00.753013360Z","packages":[{"ecosystem":"PyPI","name":"pyopenssl","purl":"pkg:pypi/pyopenssl","ranges":[">=0.14.0 <26.0.0"],"fixed":["26.0.0"]}]},{"id":"PYSEC-2026-2268","url":"https://osv.dev/vulnerability/PYSEC-2026-2268","summary":"","modified":"2026-07-13T07:15:42.074177418Z","packages":[{"ecosystem":"PyPI","name":"pyopenssl","purl":"pkg:pypi/pyopenssl","ranges":[">=0.14 <26.0.0"],"fixed":["26.0.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}