Replay Attack Affecting authlib package, versions [,1.9.0)
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-21460690
- published23 Oct 2026
- disclosed22 Oct 2026
- creditBarnabas Charumbuka
Introduced: 22 Oct 2026
NewCVE-2026-114617 (opens in a new tab)How to fix?
Upgrade authlib to version 1.9.0 or higher.
Overview
authlib is a library in building OAuth and OpenID Connect servers.
Affected versions of this package are vulnerable to Replay Attack via parse_id_token in authlib/integrations/base_client/sync_openid.py and its async counterpart, where an ID Token containing a nonce_supported: false claim causes the library to set the expected nonce to None, bypassing nonce validation entirely. An attacker who can intercept or replay an ID Token can suppress the nonce check by including this claim, allowing token replay attacks that compromise the integrity of the OpenID Connect authentication flow. Additionally, JAR (JWT Authorization Request) signature requirements can be bypassed through algorithm customization, and request_uri values are fetched without prior validation against registered URIs.