Allocation of Resources Without Limits or Throttling Affecting authlib package, versions [,1.6.5)
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-13535080
- published12 Oct 2025
- disclosed10 Oct 2025
- creditMuhammad Noman Ilyas
Introduced: 10 Oct 2025
NewCVE-2025-61920 (opens in a new tab)How to fix?
Upgrade authlib to version 1.6.5 or higher.
Overview
authlib is a library in building OAuth and OpenID Connect servers.
Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling via the extract_segment and extract_header processes. An unauthenticated attacker can exhaust system resources and disrupt service availability by submitting specially crafted tokens with excessively large base64url-encoded header or signature segments.
Workaround
This vulnerability can be mitigated by enforcing input size limits before processing tokens and applying application-level throttling to reduce amplification risk.