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Vulnerability record · CVE-2026-102270 · published 28 September 2026

CVE-2026-102270: Pyjwt project pyjwt inefficient regular expression (redos) vulnerability

Pyjwt Project · 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.

4.9 CVSS 3.1 Medium EPSS 0.21% · top 89.5% CWE-1333 · Inefficient regular expression (ReDoS)
4.9CVSS 3.1 base score
0.21%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References, 2 tagged exploit
6 Oct 2026Last modified by NVD

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/jpadilla/pyjwt/commit/8b4e233a22206b34ec1186e912e75c0b2396ac07 Patch
https://github.com/jpadilla/pyjwt/releases/tag/2.14.0 ProductRelease Notes
https://github.com/jpadilla/pyjwt/security/advisories/GHSA-jwrc-g2q2-pq5p ExploitPatchVendor Advisory
https://github.com/jpadilla/pyjwt/security/advisories/GHSA-jwrc-g2q2-pq5p ExploitPatchVendor Advisory

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Source: NIST National Vulnerability Database (record CVE-2026-102270), CISA KEV, FIRST EPSS (scores of 2026-10-07). This page is refreshed as NVD updates the record.