EEF-CVE-2026-65632

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Source

https://cna.erlef.org/osv/EEF-CVE-2026-65632.html

Import Source

https://cna.erlef.org/osv/EEF-CVE-2026-65632.json

JSON Data

https://api.osv.dev/v1/vulns/EEF-CVE-2026-65632

Aliases

CVE-2026-65632
GHSA-44hw-rpw9-mwg4

Published

2026-10-26T19:53:56Z

Modified

2026-10-26T20:11:07Z

Severity

5.1 (Medium) CVSS_V4 - CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N CVSS Calculator

Summary

ECDSA signature length is not validated in jose, allowing signature malleability

Details

Summary

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.

Database specific

{
    "capec_ids":  [
        "CAPEC-475"
    ],
    "cpe_ids":  [
        "cpe:2.3:a:potatosalad:jose:*:*:*:*:*:*:*:*"
    ],
    "cwe_ids":  [
        "CWE-347"
    ]
}

References

Credits

- Peter Ullrich - REPORTER
- Andrew Bennett - REMEDIATION_DEVELOPER
- Jonatan Männchen / EEF - ANALYST

Affected packages

Hex / jose

Package

Name: jose
Purl: pkg:hex/jose

Affected ranges

Type: SEMVER
Events: Introduced

1.0.0

Fixed

1.11.13

Affected versions

1.*

1.0.0

1.0.1

1.1.0

1.1.1

1.1.2

1.1.3

1.2.0

1.3.0

1.4.0

1.4.1

1.4.2

1.5.0

1.5.1

1.5.2

1.6.0

1.6.1

1.7.0

1.7.1

1.7.2

1.7.3

1.7.4

1.7.5

1.7.6

1.7.7

1.7.8

1.7.9

1.8.0

1.8.1

1.8.2

1.8.3

1.8.4

1.9.0

1.10.0

1.10.1

1.11.0

1.11.1

1.11.2

1.11.4

1.11.5

1.11.6

1.11.7

1.11.8

1.11.9

1.11.10

1.11.11

1.11.12

Database specific

source

"https://cna.erlef.org/osv/EEF-CVE-2026-65632.json"

Git / github.com/potatosalad/erlang-jose