{"id":"CVE-2026-28802","aliases":["GHSA-7wc2-qxgw-g8gg","PYSEC-2026-2118"],"url":"https://o3.security/vulnerability/CVE-2026-28802","summary":"Authlib: Setting `alg: none` and a blank signature appears to bypass signature verification","details":"Authlib is a Python library which builds OAuth and OpenID Connect servers. From version 1.6.5 to before version 1.6.7, previous tests involving passing a malicious JWT containing alg: none and an empty signature was passing the signature verification step without any changes to the application code when a failure was expected.. This issue has been patched in version 1.6.7.","published":"2026-03-06T06:44:26.402Z","modified":"2026-09-12T03:30:53.232194250Z","cvss":null,"epss":{"score":0.00425,"percentile":0.36242,"asOf":"2026-09-17"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"authlib","fixedVersion":"1.6.7"}],"fix":{"url":"https://github.com/authlib/authlib/commit/a61c2acb807496e67f32051b5f1b1d5ccf8f0a75","label":"authlib/authlib@a61c2ac"},"references":[{"type":"WEB","url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-28802.json"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:19375"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:4942"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:5168"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:5665"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:6309"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:6568"},{"type":"ADVISORY","url":"https://access.redhat.com/security/cve/CVE-2026-28802"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/28xxx/CVE-2026-28802.json"},{"type":"ADVISORY","url":"https://github.com/authlib/authlib/security/advisories/GHSA-7wc2-qxgw-g8gg"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-28802"},{"type":"REPORT","url":"https://bugzilla.redhat.com/show_bug.cgi?id=2445120"},{"type":"FIX","url":"https://github.com/authlib/authlib/commit/a61c2acb807496e67f32051b5f1b1d5ccf8f0a75"},{"type":"FIX","url":"https://github.com/authlib/authlib/commit/b87c32ed07b8ae7f805873e1c9cafd1016761df7"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-12T03:30:53.232194250Z"}}