{"id":"DEBIAN-CVE-2026-65625","details":"The pure-Erlang AES-GCM fallback in jose_jwa_aes derives the number of verified authentication tag bits from the attacker-supplied tag itself. In the {aes_gcm, Bits} clause of block_decrypt/4, the incoming tag is guarded only by is_binary/1, with no check on its length. Verification in gcm_block_decrypt/6 then computes TBits = bit_size(T) and compares only those bits of the real 128-bit tag. An attacker who controls a JWE token can truncate the authentication tag to as little as 8 bits, so only 8 bits are ever checked. This reduces forgery resistance from 2^-128 to 2^-8, and a forged ciphertext is reliably accepted as authentic within 256 attempts without knowledge of the key (an authentication tag forgery and integrity bypass). Supplying a tag longer than 128 bits instead causes a badmatch that crashes the decrypting process. The fallback is reached through the public JWE decryption path whenever AES-GCM is not provided by a native crypto NIF, for example on FIPS or stripped or older OTP builds.  This issue affects jose: from 1.2.0 before 1.11.13.","modified":"2026-10-27T17:00:07.809023961Z","published":"2026-10-26T20:17:57.910Z","upstream":["CVE-2026-65625"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-65625"}],"affected":[{"package":{"name":"erlang-jose","ecosystem":"Debian:12","purl":"pkg:deb/debian/erlang-jose?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.11.10-1","1.11.10-1~bpo12+1","1.11.12-1","1.11.12-1.1","1.11.12-2","1.11.12-2~bpo13+1","1.11.12-3","1.11.12-3~bpo13+1","1.11.5-1","1.11.6-1","1.11.6-1~bpo12+1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-65625.json"}},{"package":{"name":"erlang-jose","ecosystem":"Debian:13","purl":"pkg:deb/debian/erlang-jose?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.11.10-1","1.11.12-1","1.11.12-1.1","1.11.12-2","1.11.12-2~bpo13+1","1.11.12-3","1.11.12-3~bpo13+1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-65625.json"}},{"package":{"name":"erlang-jose","ecosystem":"Debian:14","purl":"pkg:deb/debian/erlang-jose?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.11.10-1","1.11.12-1","1.11.12-1.1","1.11.12-2","1.11.12-2~bpo13+1","1.11.12-3","1.11.12-3~bpo13+1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-65625.json"}}],"schema_version":"1.9.2","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X"}]}