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Fencer Vulns
high 7.5

CVE-2026-33204 json

SimpleJWT has an Unauthenticated Denial of Service via JWE header tampering

published 2026-03-18 7 mo ago modified 2026-06-17 4 mo ago also GHSA-xw36-67f8-339x , EUVD-2026-13871

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 43%
public exploits
0
none known

Summary

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.

Patch / fix

  • packagist kelvinmo/simplejwt 1.1.1
  • kelvinmo simplejwt 1.1.1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-33204 updated cvss 5.9

SimpleJWT: SimpleJWT: Denial of Service via JWE header tampering

  • Red Hat Ansible Automation Platform 2 python-djangorestframework-simplejwt, python3x-djangorestframework-simplejwt, python3.11-djangorestframework-simplejwt, python3.12-djangorestframework-simplejwt
    affected: workaround, no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
7 mo ago

Exploit prediction

0.50% chance of exploitation in the next 30 days, higher than 43% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/kelvinmo/simplejwt/security/advisories/GHSA-xw36-67f8-339x referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
packagist kelvinmo/simplejwt
<1.1.1
1.1.1

Affected products

  • kelvinmo simplejwt

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.