CVE-2026-102265: CWE-674: Uncontrolled Recursion in jpadilla pyjwt
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.
AI Analysis
Technical Summary
PyJWT, a Python library implementing JSON Web Token standards, has a vulnerability (CWE-674) in versions >=2.13.0 <2.14.0 where the PyJWS._load function does not handle RecursionError exceptions raised by deeply nested token headers during JSON parsing. The parser only catches ValueError, allowing RecursionError to escape the error handling hierarchy. This results in an unauthenticated malformed token causing a server-side failure (HTTP 500). The vulnerability is fixed in version 2.14.0.
Potential Impact
The vulnerability allows an unauthenticated attacker to cause a denial of service by submitting a malformed token that triggers a RecursionError, leading to a request-level failure and HTTP 500 response. There is no impact on confidentiality or integrity, only availability is affected.
Mitigation Recommendations
Upgrade PyJWT to version 2.14.0 or later, where this uncontrolled recursion issue is fixed. No other mitigations are indicated or necessary.
CVE-2026-102265: CWE-674: Uncontrolled Recursion in jpadilla pyjwt
Description
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.
CVSS v3.1
Score 5.3medium
Affected software
jpadilla
pyjwt
Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
PyJWT, a Python library implementing JSON Web Token standards, has a vulnerability (CWE-674) in versions >=2.13.0 <2.14.0 where the PyJWS._load function does not handle RecursionError exceptions raised by deeply nested token headers during JSON parsing. The parser only catches ValueError, allowing RecursionError to escape the error handling hierarchy. This results in an unauthenticated malformed token causing a server-side failure (HTTP 500). The vulnerability is fixed in version 2.14.0.
Potential Impact
The vulnerability allows an unauthenticated attacker to cause a denial of service by submitting a malformed token that triggers a RecursionError, leading to a request-level failure and HTTP 500 response. There is no impact on confidentiality or integrity, only availability is affected.
Mitigation Recommendations
Upgrade PyJWT to version 2.14.0 or later, where this uncontrolled recursion issue is fixed. No other mitigations are indicated or necessary.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-09-28T20:11:16.658Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6abad639f7a7c54106343f75
Added to database: 09/28/2026, 21:03:53 UTC
Last enriched: 09/28/2026, 21:17:49 UTC
Last updated: 09/29/2026, 02:48:19 UTC
Views: 8
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.