by Kastro
Paper/Archive/CVE-2026-114616

CVE-2026-114616

authlib authlib — Authlib accepts an empty HMAC key, allowing JWS/JWT signature forgery (HS256/HS384/HS512)

EPSS 0.2%CVSS 9.1
critical.is priorityof 100
30
CVSS 9.1 (NVD)9.1 / 10 × 3027.3Not in CISA KEV+300.0EPSS percentile 11.5.115 × 202.3No public exploit+100.0SSVC exploitation: unknown+100.0
Description · from the CVE record

Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to 1.9.1, Authlib's OctKey.import_key() and HMAC signing and verification path accept zero-length key material. If an application's secret lookup can return an empty string or empty bytes, a remote attacker can compute the deterministic HS256, HS384, or HS512 signature for arbitrary token claims and have Authlib treat the token as authentic. This issue is fixed in version 1.9.1.

Affected

ProductAffectedFixed inSource
authlib< 1.9.1–CNA

Scores by source

NVD9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
GitHub_M (CNA)7.4CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

References

refgithub.com/authlib/authlib/security/advisories/GHSA-8m4g-j4wp-wgcgrefgithub.com/authlib/authlib/commit/4ff30db442c70e29486e1982cb0ad37c037f5f4brefgithub.com/authlib/authlib/releases/tag/v1.9.1