CVE-2026-65632 Affecting erlang-jose package, versions *
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-DEBIAN13-ERLANGJOSE-21757344
- published28 Oct 2026
- disclosed26 Oct 2026
Introduced: 26 Oct 2026
NewCVE-2026-65632 (opens in a new tab)How to fix?
There is no fixed version for Debian:13 erlang-jose.
NVD Description
Note: Versions mentioned in the description apply only to the upstream erlang-jose package and not the erlang-jose package as distributed by Debian.
See How to fix? for Debian:13 relevant fixed versions and status.
The jose library accepts ECDSA (ES256, ES256K, ES384, and ES512) JWS signatures of a non-canonical length. When verifying an ECDSA signature, jose_jwk_kty_ec:verify/4 in src/jwk/jose_jwk_kty_ec.erl splits the raw signature in half by its actual byte length (split_binary(Signature, byte_size(Signature) div 2)) instead of enforcing the fixed length required by RFC 7518 §3.4, and then decodes each half with crypto:bytes_to_integer/1, which ignores leading zero bytes.
As a result, an attacker who holds one valid token can prepend leading zero bytes to each of the R and S halves to produce longer signatures that still split evenly and decode to the same (r, s) pair, so many distinct signature byte strings all verify against the same key (signature malleability). This does not allow forging new payloads or impersonating a signer, because the underlying (r, s) values are unchanged. It does defeat any security control that assumes a valid token or its signature is unique, such as token-revocation-by-hash, replay or idempotency caches, and deduplication logic.
This issue affects jose: from 1.0.0 before 1.11.13.
References
- https://security-tracker.debian.org/tracker/CVE-2026-65632
- https://cna.erlef.org/cves/CVE-2026-65632.html
- https://github.com/potatosalad/erlang-jose/commit/72ce1866622b9329347dc52a94173ac0317bc9cf
- https://github.com/potatosalad/erlang-jose/commit/a7746ecd4950f85a393136e449a91dac62b5c429
- https://github.com/potatosalad/erlang-jose/security/advisories/GHSA-44hw-rpw9-mwg4
- https://osv.dev/vulnerability/EEF-CVE-2026-65632