CVE-2026-102270: PyJWT: ReDoS vulnerability when calling the `is_pem_format` function.

September 30, 2026

There is a Re-DoS vulnerability in the is_pem_format function which results in a intesive CPU usage if an attacker is been able to provide a custom certificate.

References

github.com/advisories/GHSA-jwrc-g2q2-pq5p
github.com/jpadilla/pyjwt/commit/8b4e233a22206b34ec1186e912e75c0b2396ac07
github.com/jpadilla/pyjwt/releases/tag/2.14.0
github.com/jpadilla/pyjwt/security/advisories/GHSA-jwrc-g2q2-pq5p
nvd.nist.gov/vuln/detail/CVE-2026-102270

Code Behaviors & Features

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