CVE-2026-102270

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 3.1

4.9CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

EPSS

0.2% chance of exploitation in the next 30 days; higher than 15% of CVEs (scores of 2026-10-25)

CWE

CWE-1333

Published

2026-09-28

Modified

2026-10-06

Record from

the NVD, synced 2026-10-19

Affected

• pyjwt_project:pyjwt

Packages (OSV)

References

• https://github.com/jpadilla/pyjwt/commit/8b4e233a22206b34ec1186e912e75c0b2396ac07
• https://github.com/jpadilla/pyjwt/releases/tag/2.14.0
• https://github.com/jpadilla/pyjwt/security/advisories/GHSA-jwrc-g2q2-pq5p
• https://github.com/jpadilla/pyjwt/security/advisories/GHSA-jwrc-g2q2-pq5p

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