CVE-2026-102270 — PyJWT: ReDoS vulnerability when calling the `is_pem_format` function.
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 o…
Published: 2026-09-28 · CVSS: 4.4 · CVSS 3.1
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.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7