CVE-2026-32597: CWE-345: Insufficient Verification of Data Authenticity in jpadilla pyjwt
PyJWT is a JSON Web Token implementation in Python. Prior to 2.12.0, PyJWT does not validate the crit (Critical) Header Parameter defined in RFC 7515 §4.1.11. When a JWS token contains a crit array listing extensions that PyJWT does not understand, the library accepts the token instead of rejecting it. This violates the MUST requirement in the RFC. This vulnerability is fixed in 2.12.0.
AI Analysis
Technical Summary
PyJWT, a Python library for JSON Web Tokens, before version 2.12.0, fails to enforce the mandatory validation of the 'crit' header parameter as specified in RFC 7515 §4.1.11. When a JWS token includes a 'crit' array listing extensions that PyJWT does not understand, the library incorrectly accepts the token rather than rejecting it. This behavior constitutes insufficient verification of data authenticity (CWE-345) and improper handling of critical extensions (CWE-863). The vulnerability has a CVSS 3.1 score of 7.5, indicating high severity, and was addressed by the vendor in version 2.12.0.
Potential Impact
This vulnerability allows attackers to craft JSON Web Tokens with unrecognized critical extensions that PyJWT will accept without proper validation. This can lead to acceptance of tokens that should be rejected, potentially enabling unauthorized actions or bypassing security controls relying on token validation. There is no indication of known exploits in the wild at this time.
Mitigation Recommendations
Upgrade PyJWT to version 2.12.0 or later, where the validation of the 'crit' header parameter is correctly implemented in accordance with RFC 7515 §4.1.11. No other mitigation is required as the vendor has provided an official fix.
CVE-2026-32597: CWE-345: Insufficient Verification of Data Authenticity in jpadilla pyjwt
Description
PyJWT is a JSON Web Token implementation in Python. Prior to 2.12.0, PyJWT does not validate the crit (Critical) Header Parameter defined in RFC 7515 §4.1.11. When a JWS token contains a crit array listing extensions that PyJWT does not understand, the library accepts the token instead of rejecting it. This violates the MUST requirement in the RFC. This vulnerability is fixed in 2.12.0.
CVSS v3.1
Score 7.5high
Affected software
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
PyJWT, a Python library for JSON Web Tokens, before version 2.12.0, fails to enforce the mandatory validation of the 'crit' header parameter as specified in RFC 7515 §4.1.11. When a JWS token includes a 'crit' array listing extensions that PyJWT does not understand, the library incorrectly accepts the token rather than rejecting it. This behavior constitutes insufficient verification of data authenticity (CWE-345) and improper handling of critical extensions (CWE-863). The vulnerability has a CVSS 3.1 score of 7.5, indicating high severity, and was addressed by the vendor in version 2.12.0.
Potential Impact
This vulnerability allows attackers to craft JSON Web Tokens with unrecognized critical extensions that PyJWT will accept without proper validation. This can lead to acceptance of tokens that should be rejected, potentially enabling unauthorized actions or bypassing security controls relying on token validation. There is no indication of known exploits in the wild at this time.
Mitigation Recommendations
Upgrade PyJWT to version 2.12.0 or later, where the validation of the 'crit' header parameter is correctly implemented in accordance with RFC 7515 §4.1.11. No other mitigation is required as the vendor has provided an official fix.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-03-12T14:54:24.269Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 69b3375b2f860ef943024596
Added to database: 3/12/2026, 9:59:55 PM
Last enriched: 5/6/2026, 1:42:55 AM
Last updated: 6/11/2026, 9:23:43 AM
Views: 339
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