CVE-2026-102270: CWE-1333: Inefficient Regular Expression Complexity in jpadilla pyjwt
PyJWT is a Python implementation of JSON Web Token standards. Prior to 2.14.0, PyJWT is_pem_format is affected because lazy PEM regular expression backtracks extensively. This occurs when a certificate-like input contains repeated BEGIN markers without a matching END marker. As a result, is_pem_format performs unbounded backtracking while searching for a PEM end marker. Consequently, an attacker can cause intensive CPU consumption. This issue is fixed in version 2.14.0.
AI Analysis
Technical Summary
CVE-2026-102270 describes a vulnerability in the PyJWT Python library's is_pem_format function, where a lazy PEM regular expression performs extensive backtracking on inputs containing repeated BEGIN markers without matching END markers. This inefficiency causes unbounded CPU consumption, enabling an attacker to cause intensive resource usage. The vulnerability is resolved in PyJWT version 2.14.0.
Potential Impact
An attacker can cause high CPU usage on systems running vulnerable PyJWT versions by supplying specially crafted certificate-like inputs that trigger excessive regular expression backtracking. This results in a denial-of-service condition due to intensive CPU consumption. There is no impact on confidentiality or integrity.
Mitigation Recommendations
Upgrade PyJWT to version 2.14.0 or later, where this inefficient regular expression backtracking issue has been fixed.
CVE-2026-102270: CWE-1333: Inefficient Regular Expression Complexity in jpadilla pyjwt
Description
PyJWT is a Python implementation of JSON Web Token standards. Prior to 2.14.0, PyJWT is_pem_format is affected because lazy PEM regular expression backtracks extensively. This occurs when a certificate-like input contains repeated BEGIN markers without a matching END marker. As a result, is_pem_format performs unbounded backtracking while searching for a PEM end marker. Consequently, an attacker can cause intensive CPU consumption. This issue is fixed in version 2.14.0.
CVSS v3.1
Score 4.4medium
Affected software
jpadilla
pyjwt
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-102270 describes a vulnerability in the PyJWT Python library's is_pem_format function, where a lazy PEM regular expression performs extensive backtracking on inputs containing repeated BEGIN markers without matching END markers. This inefficiency causes unbounded CPU consumption, enabling an attacker to cause intensive resource usage. The vulnerability is resolved in PyJWT version 2.14.0.
Potential Impact
An attacker can cause high CPU usage on systems running vulnerable PyJWT versions by supplying specially crafted certificate-like inputs that trigger excessive regular expression backtracking. This results in a denial-of-service condition due to intensive CPU consumption. There is no impact on confidentiality or integrity.
Mitigation Recommendations
Upgrade PyJWT to version 2.14.0 or later, where this inefficient regular expression backtracking issue has been fixed.
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: 6abad294f7a7c541062fe5be
Added to database: 09/28/2026, 20:48:20 UTC
Last enriched: 09/28/2026, 21:02:59 UTC
Last updated: 09/29/2026, 02:48:30 UTC
Views: 7
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