CVE-2026-101918: CWE-248: Uncaught Exception in jpadilla pyjwt
PyJWT is a Python implementation of JSON Web Token standards. From 2.0.0a1 until 2.15.0, PyJWT PyJWKClient.get_signing_key_from_jwt is affected because payload parser catches ValueError but not RecursionError. This occurs when an attacker-controlled recursively nested payload reaches json.loads. As a result, documented PyJWT exception handling does not contain the failure. Consequently, an unauthenticated request can raise an exception that may produce an HTTP 500 response. The advisory-defined affected implementation also includes jwt/api_jwt.py, verify_signature=False. This issue is fixed in version 2.15.0.
AI Analysis
Technical Summary
PyJWT, a Python library implementing JSON Web Token standards, has a vulnerability in the PyJWKClient.get_signing_key_from_jwt method where the payload parser catches ValueError but not RecursionError. When an attacker sends a recursively nested payload that triggers json.loads to raise a RecursionError, the exception is uncaught, resulting in an HTTP 500 response. This affects versions from 2.0.0a1 through 2.15.0 (exclusive). The vulnerability is addressed in version 2.15.0.
Potential Impact
An unauthenticated attacker can cause the PyJWT library to raise an uncaught exception leading to a denial of service via an HTTP 500 response. There is no impact on confidentiality or integrity, only availability is affected.
Mitigation Recommendations
Upgrade PyJWT to version 2.15.0 or later where this issue is fixed. No other mitigations are specified or required.
CVE-2026-101918: CWE-248: Uncaught Exception in jpadilla pyjwt
Description
PyJWT is a Python implementation of JSON Web Token standards. From 2.0.0a1 until 2.15.0, PyJWT PyJWKClient.get_signing_key_from_jwt is affected because payload parser catches ValueError but not RecursionError. This occurs when an attacker-controlled recursively nested payload reaches json.loads. As a result, documented PyJWT exception handling does not contain the failure. Consequently, an unauthenticated request can raise an exception that may produce an HTTP 500 response. The advisory-defined affected implementation also includes jwt/api_jwt.py, verify_signature=False. This issue is fixed in version 2.15.0.
CVSS v3.1
Score 5.3medium
Affected software
jpadilla
pyjwt
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
PyJWT, a Python library implementing JSON Web Token standards, has a vulnerability in the PyJWKClient.get_signing_key_from_jwt method where the payload parser catches ValueError but not RecursionError. When an attacker sends a recursively nested payload that triggers json.loads to raise a RecursionError, the exception is uncaught, resulting in an HTTP 500 response. This affects versions from 2.0.0a1 through 2.15.0 (exclusive). The vulnerability is addressed in version 2.15.0.
Potential Impact
An unauthenticated attacker can cause the PyJWT library to raise an uncaught exception leading to a denial of service via an HTTP 500 response. There is no impact on confidentiality or integrity, only availability is affected.
Mitigation Recommendations
Upgrade PyJWT to version 2.15.0 or later where this issue is fixed. No other mitigations are specified or required.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-09-28T15:55:37.908Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6abacf14f7a7c541062b9a50
Added to database: 09/28/2026, 20:33:24 UTC
Last enriched: 09/28/2026, 20:48:08 UTC
Last updated: 09/29/2026, 02:48:04 UTC
Views: 9
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