jpadilla PyJWT up to 2.14.x Payload Parser jwt/api_jwt.py PyJWKClient.get_signing_key_from_jwt recursion

Summaryinfo

A vulnerability was found in jpadilla PyJWT up to 2.14.x and classified as problematic. Affected by this issue is the function PyJWKClient.get_signing_key_from_jwt of the file jwt/api_jwt.py of the component Payload Parser. Such manipulation leads to recursion. This vulnerability is referenced as CVE-2026-101918. It is possible to launch the attack remotely. No exploit is available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in jpadilla PyJWT up to 2.14.x and classified as problematic. Affected by this issue is the function PyJWKClient.get_signing_key_from_jwt of the file jwt/api_jwt.py of the component Payload Parser. The manipulation with an unknown input leads to a recursion vulnerability. Using CWE to declare the problem leads to CWE-674. The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack. Impacted is availability. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-101918 since 09/28/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1499 by the MITRE ATT&CK project.

Upgrading to version 2.15.0 eliminates this vulnerability.

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Productinfo

Vendor

• jpadilla

Name

• PyJWT

Version

• 2.0
• 2.1
• 2.2
• 2.3
• 2.4
• 2.5
• 2.6
• 2.7
• 2.8
• 2.9
• 2.10
• 2.11
• 2.12
• 2.13
• 2.14

Website

• Product: https://github.com/jpadilla/pyjwt/

CPE 2.3info

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CPE 2.2info

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