CVE-2026-102270CWE-1333

CVE-2026-102270

Medium · published September 29, 2026

CVSS v3.1
4.4
EPSS
0%
Percentile
10.9
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
4.4 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H
CVSS v4.0
Not supplied
EPSS
0.00212 · 10.9th percentile
Weakness
CWE-1333 · Inefficient Regular Expression Complexity
Published
2026-09-29T01:17Z
Affected products (1)
ProductVersionsFixed in
pyjwt_project/pyjwt< 2.14.02.14.0
References (4)
https://github.com/jpadilla/pyjwt/commit/8b4e233a22206b34ec1186e912e75c0b2396ac07 · [email protected]https://github.com/jpadilla/pyjwt/releases/tag/2.14.0 · [email protected]https://github.com/jpadilla/pyjwt/security/advisories/GHSA-jwrc-g2q2-pq5p · [email protected]https://github.com/jpadilla/pyjwt/security/advisories/GHSA-jwrc-g2q2-pq5p · 134c704f-9b21-4f2e-91b3-4a467353bcc0
EPSS history
Timeline
  • 30 SEP 03:24Z
    EPSS moved — → 0%
    epss
  • 28 SEP 20:29Z
    PyJWT: ReDoS vulnerability when calling the `is_pem_format` function.
    cvelistv5