CVE-2026-33204

SimpleJWT has an Unauthenticated Denial of Service via JWE header tampering

SimpleJWT is a simple JSON web token library written in PHP. Prior to version 1.1.1, an unauthenticated attacker can perform a Denial of Service via JWE header tampering when PBES2 algorithms are used. Applications that call JWE::decrypt() on attacker-controlled JWEs using PBES2 algorithms are affected. This issue has been patched in version 1.1.1.

Affected

kelvinmo · simplejwt

CVSS v3.1 GITHUB

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

EPSS

0.56% chance of exploitation in the next 30 days, 45th percentile

Published

2026-03-20

Updated

2026-03-24

Proof-of-concept exploits (1)

• advisories/GHSA-xw36-67f8-339x

Security advisories

• kelvinmo/simplejwt/security/advisories/GHSA-xw36-67f8-339x
• kelvinmo/simplejwt/releases/tag/v1.1.1

References

• CVE Record
• NVD entry