Incorrect Authorization Affecting authlib package, versions [,1.6.4)
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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Start learning- Snyk IDSNYK-PYTHON-AUTHLIB-13003878
- published22 Sept 2025
- disclosed22 Sept 2025
- creditMuhammad Noman Ilyas
Introduced: 22 Sep 2025
CVE-2025-59420 (opens in a new tab)How to fix?
Upgrade authlib to version 1.6.4 or higher.
Overview
authlib is a library in building OAuth and OpenID Connect servers.
Affected versions of this package are vulnerable to Incorrect Authorization via the deserialize_compact function. An attacker can bypass intended authorization policies by crafting a signed token with unknown critical header parameters, which are improperly accepted and processed.