medium5.3
CVE-2026-102265
PyJWT: Uncaught RecursionError in jwt.decode() on deeply nested token header
Impact
PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, PyJWS._load in jwt/api_jws.py is affected because parser catches ValueError but not RecursionError. This occurs when a deeply nested token header reaches json.loads. As a result, RecursionError escapes the documented PyJWT error hierarchy. Consequently, an unauthenticated malformed token can cause a request-level failure and HTTP 500. This issue is fixed in version 2.14.0.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| pip | pyJWT | >= 2.13.0, < 2.14.0 | 2.14.0 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Pyjwt Project | Pyjwt | Version 2.13.0 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-8wjv-2p76-3863
- https://github.com/jpadilla/pyjwt/security/advisories/GHSA-8wjv-2p76-3863
- https://nvd.nist.gov/vuln/detail/CVE-2026-102265
- https://github.com/jpadilla/pyjwt/commit/06573692ebcdec8831c3927513b3e87c31fbbb62
- https://github.com/jpadilla/pyjwt/releases/tag/2.14.0