{"id":"UBUNTU-CVE-2026-49852","details":"joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to 1.6.8, joserfc.jwt.decode accepts attacker-forged HMAC-signed tokens when the caller-supplied verification key is the empty string or None, because HMACAlgorithm.sign and HMACAlgorithm.verify in src/joserfc/_rfc7518/jws_algs.py pass the output of OctKey.get_op_key(...) to hmac.new(...) and OctKey.import_key in src/joserfc/_rfc7518/oct_key.py only emits a SecurityWarning for keys shorter than 14 bytes without rejecting zero-length input. This issue is fixed in version 1.6.8.","modified":"2026-07-29T10:16:52.459661187Z","published":"2026-07-17T20:17:00Z","upstream":["CVE-2026-49852"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-49852"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-49852"},{"type":"REPORT","url":"https://github.com/authlib/joserfc/security/advisories/GHSA-gg9x-qcx2-xmrh"}],"affected":[{"package":{"name":"joserfc","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/joserfc?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.2-1","1.4.0-1","1.4.1-1","1.4.3-1","1.5.0-1","1.6.2-1"],"ecosystem_specific":{"binaries":[{"binary_name":"python3-joserfc","binary_version":"1.6.2-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-49852.json"}}],"schema_version":"1.7.5","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"},{"type":"Ubuntu","score":"medium"}]}