Improper Verification of Cryptographic Signature Affecting authlib package, versions [,1.9.1)
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
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-PYTHON-AUTHLIB-21460695
- published23 Oct 2026
- disclosed22 Oct 2026
- creditclzoom, tonghuaroot (童话), Sanjeev Kumar
Introduced: 22 Oct 2026
NewCVE-2026-114616 (opens in a new tab)How to fix?
Upgrade authlib to version 1.9.1 or higher.
Overview
authlib is a library in building OAuth and OpenID Connect servers.
Affected versions of this package are vulnerable to Improper Verification of Cryptographic Signature via the _check_key method in authlib/jose/rfc7518/oct_key.py, where an empty octet-sequence (oct) key is accepted without error for HMAC-based algorithms (HS256, HS384, HS512). An attacker can forge valid JWS signatures by supplying an empty string as the HMAC key, bypassing signature verification entirely.