PyJWT: ReDoS vulnerability when calling the `is_pem_format` function. — GHSA-JWRC-G2Q2-PQ5P

Summary

### Summary 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. ### Details The problem is that the lazy quantifier `.+?` will always first try to match as little as possible until it finds a `---- END`. Normally this means the complexity of this should be O(N). However, by providing an input which…

Timeline

Published by source

2026-09-30

Risk context

• Reported severity or threat level: medium.
• Reported CVSS score: 4.4 out of 10.
• Reported EPSS value: 0.00192.
• Review exposure for the affected product or family: pip: pyjwt.

Product

pip: pyjwt

What to do

General, cautious steps (verify details in the official source):

• Review exposure and plan remediation based on risk and environment.
• Identify affected product versions in your inventory and verify whether you are impacted.
• Apply vendor patches/updates or recommended mitigations as soon as available.
• Read the official advisory for exact affected versions and remediation steps.

Official advisory

• Read the official source
• CVE Record
• NVD

Evidence and provenance

Canonical advisory ID

GHSA-JWRC-G2Q2-PQ5P

Source

GitHub

Vendor

GitHub

Published by source

2026-09-30

Last source activity

2026-09-30

Additional identifiers

CVE-2026-102270

Curated by

hlukh.ch

Related advisories and connections

These advisories are connected by shared CVE, product, vendor, source, or time signals.