{"id":"CVE-2026-114616","title":"Authlib accepts an empty HMAC key, allowing JWS/JWT signature forgery (HS256/HS384/HS512)","summary":"Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to 1.9.1, Authlib's OctKey.import_key() and HMAC signing and verification path accept zero-length key material. If an application's secret lookup can return…","severity":"high","cvss":7.4,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N","cvssSource":"cna","cwe":["CWE-287","CWE-326","CWE-1391"],"vendor":"authlib","product":"authlib","affected":["authlib < 1.9.1"],"published":"2026-10-22","updated":"2026-10-22","sourceUpdated":"2026-10-22T21:14:03.060Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-114616","references":[{"url":"https://github.com/authlib/authlib/security/advisories/GHSA-8m4g-j4wp-wgcg","label":"https://github.com/authlib/authlib/security/advisories/GHSA-8m4g-j4wp-wgcg"},{"url":"https://github.com/authlib/authlib/commit/4ff30db442c70e29486e1982cb0ad37c037f5f4b","label":"https://github.com/authlib/authlib/commit/4ff30db442c70e29486e1982cb0ad37c037f5f4b"},{"url":"https://github.com/authlib/authlib/releases/tag/v1.9.1","label":"https://github.com/authlib/authlib/releases/tag/v1.9.1"}],"tags":["cve.org"],"ingestedAt":"2026-10-22T22:00:50.442Z","slug":"CVE-2026-114616","body":"## Overview\n\nAuthlib is a Python library which builds OAuth and OpenID Connect servers. Prior to 1.9.1, Authlib's OctKey.import_key() and HMAC signing and verification path accept zero-length key material. If an application's secret lookup can return an empty string or empty bytes, a remote attacker can compute the deterministic HS256, HS384, or HS512 signature for arbitrary token claims and have Authlib treat the token as authentic. This issue is fixed in version 1.9.1.\n\n## Affected\n\n- `authlib < 1.9.1`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":40.7,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}