CVE-2026-102270
Medium
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.
SeverityMedium
CVSS4.4
Exploit probability—
ProductPyjwt
PublishedSep 28, 2026
First seenSep 28, 2026
Weakness typeCWE-1333CWE-1333
How to fix
Update
- pyjwt_project pyjwt2.14.0 or later
- pyjwt2.14.0 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| pyjwt_project pyjwt | v < 2.14.0 | 2.14.0 |
| pyjwtPyPI | v < 2.14.0 | 2.14.0 |
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