{"id":"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.","aliases":["GHSA-7wc2-qxgw-g8gg","PYSEC-2026-2118"],"modified":"2026-09-12T03:30:53.232194250Z","published":"2026-03-06T06:44:26.402Z","database_specific":{"cwe_ids":["CWE-347"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/28xxx/CVE-2026-28802.json","cna_assigner":"GitHub_M"},"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"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/authlib/authlib","events":[{"introduced":"9ec42561cd1a81b518598d252f8adbcf446f7419"},{"fixed":"38e872a3f5b97d2658507acc8762a4e18adaa50e"},{"fixed":"a61c2acb807496e67f32051b5f1b1d5ccf8f0a75"},{"fixed":"b87c32ed07b8ae7f805873e1c9cafd1016761df7"}],"database_specific":{"cpe":"cpe:2.3:a:authlib:authlib:*:*:*:*:*:*:*:*","extracted_events":[{"introduced":"1.6.5"},{"fixed":"1.6.7"}],"source":["CPE_RANGE","REFERENCES"]}}],"versions":["v1.6.6","v1.6.5"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-28802.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P"}]}