{"id":"DEBIAN-CVE-2026-27962","details":"Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to version 1.6.9, a JWK Header Injection vulnerability in authlib's JWS implementation allows an unauthenticated attacker to forge arbitrary JWT tokens that pass signature verification. When key=None is passed to any JWS deserialization function, the library extracts and uses the cryptographic key embedded in the attacker-controlled JWT jwk header field. An attacker can sign a token with their own private key, embed the matching public key in the header, and have the server accept the forged token as cryptographically valid — bypassing authentication and authorization entirely. This issue has been patched in version 1.6.9.","modified":"2026-09-11T18:47:36.615209166Z","published":"2026-03-16T18:16:07.383Z","upstream":["CVE-2026-27962"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-27962"}],"affected":[{"package":{"name":"python-authlib","ecosystem":"Debian:12","purl":"pkg:deb/debian/python-authlib?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.2.0-1+deb12u2"}]}],"versions":["1.2.0-1","1.2.0-1+deb12u1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-27962.json"}},{"package":{"name":"python-authlib","ecosystem":"Debian:13","purl":"pkg:deb/debian/python-authlib?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.6.0-1","1.6.0-1+deb13u1","1.6.1-1","1.6.3-1","1.6.4-1","1.6.5-1","1.6.6-1","1.6.7-1","1.6.8-1","1.6.9-1","1.7.0-1","1.7.2-1","1.7.2-2"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-27962.json"}},{"package":{"name":"python-authlib","ecosystem":"Debian:14","purl":"pkg:deb/debian/python-authlib?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.6.9-1"}]}],"versions":["1.6.0-1","1.6.1-1","1.6.3-1","1.6.4-1","1.6.5-1","1.6.6-1","1.6.7-1","1.6.8-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-27962.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N"}]}