CVE-2026-65625

NameCVE-2026-65625
DescriptionThe 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.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs1152299

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
erlang-jose (PTS)bookworm1.11.5-1vulnerable
trixie1.11.10-1vulnerable
forky, sid1.11.12-3vulnerable

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
erlang-josesource(unstable)(unfixed)1152299

Notes

https://github.com/potatosalad/erlang-jose/security/advisories/GHSA-6gxw-6f7r-cjr6
https://cna.erlef.org/cves/CVE-2026-65625.html
https://osv.dev/vulnerability/EEF-CVE-2026-65625
Introduced with: https://github.com/potatosalad/erlang-jose/commit/8848b172575fb7d7e1e2977e8ae0a21678d2157a (1.2.0)
Fixed by: https://github.com/potatosalad/erlang-jose/commit/3fa1f8e3efda0da5ce6f4c9984789f979dc02740 (1.11.13)

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