Uncontrolled Recursion Affecting pyjwt package, versions [2.13.0,2.14.0)
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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Start learning- Snyk IDSNYK-PYTHON-PYJWT-20246764
- published29 Sept 2026
- disclosed28 Sept 2026
- creditNivid42
Introduced: 28 Sep 2026
NewCVE-2026-102265 (opens in a new tab)How to fix?
Upgrade PyJWT to version 2.14.0 or higher.
Overview
PyJWT is a Python implementation of RFC 7519.
Affected versions of this package are vulnerable to Uncontrolled Recursion via the _load method in jwt/api_jws.py when parsing a JWT with a deeply nested recursive JSON structure in the header. An attacker can supply a JWT whose header contains deeply nested JSON objects, triggering unbounded recursion in the JSON parser and causing a RecursionError that crashes the process. Prior to the fix, RecursionError was not caught alongside ValueError, so it propagated as an unhandled exception instead of being converted to a DecodeError.