{"id":"CVE-2026-27459","aliases":["GHSA-5pwr-322w-8jr4","PYSEC-2026-2269"],"url":"https://o3.security/vulnerability/CVE-2026-27459","summary":"pyOpenSSL DTLS cookie callback buffer overflow","details":"pyOpenSSL is a Python wrapper around the OpenSSL library. Starting in version 22.0.0 and prior to version 26.0.0, if a user provided callback to `set_cookie_generate_callback` returned a cookie value greater than 256 bytes, pyOpenSSL would overflow an OpenSSL provided buffer. Starting in version 26.0.0, cookie values that are too long are now rejected.","published":"2026-03-17T23:34:28.483Z","modified":"2026-09-12T03:30:23.146310478Z","cvss":null,"epss":{"score":0.00704,"percentile":0.51608,"asOf":"2026-09-16"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"pyopenssl","fixedVersion":"26.0.0"}],"fix":{"url":"https://github.com/pyca/pyopenssl/commit/57f09bb4bb051d3bc2a1abd36e9525313d5cd408","label":"pyca/pyopenssl@57f09bb"},"references":[{"type":"WEB","url":"https://github.com/pyca/pyopenssl/blob/358cbf29c4e364c59930e53a270116249581eaa3/CHANGELOG.rst"},{"type":"WEB","url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27459.json"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:10754"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:11856"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:11916"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:11996"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:13508"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:13512"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:13545"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:13553"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:14835"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:14873"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:14874"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:19375"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:21017"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:22465"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:24853"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:48085"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:48758"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:59153"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:7224"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:8437"},{"type":"ADVISORY","url":"https://access.redhat.com/security/cve/CVE-2026-27459"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27459.json"},{"type":"ADVISORY","url":"https://github.com/pyca/pyopenssl/security/advisories/GHSA-5pwr-322w-8jr4"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-27459"},{"type":"REPORT","url":"https://bugzilla.redhat.com/show_bug.cgi?id=2448503"},{"type":"FIX","url":"https://github.com/pyca/pyopenssl/commit/57f09bb4bb051d3bc2a1abd36e9525313d5cd408"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-12T03:30:23.146310478Z"}}