CVE-2026-114616

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

State: Published
Severity: 7.4 High
Published: Oct 22, 2026
Updated: Oct 30, 2026
Reserved: Oct 21, 2026

Description

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.

Scores

CVSS	Score	Vector	Source
3.1	7.4 High	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N	GitHub_M

Weaknesses

CWE-287 Improper Authentication
CWE-326 Inadequate Encryption Strength
CWE-1391 Use of Weak Credentials

Affected Products

Product	Versions
authlibauthlib	< 1.9.1Affected

References

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