CVE-2026-33204
SimpleJWT has an Unauthenticated Denial of Service via JWE header tampering
Description
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.
INFO
Published Date :
March 20, 2026, 11:16 p.m.
Last Modified :
March 20, 2026, 11:16 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-33204
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Update SimpleJWT to version 1.1.1 or later.
- Ensure PBES2 algorithms are secured against tampering.
- Review JWE decryption input validation.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-33204.
| URL | Resource |
|---|---|
| https://github.com/kelvinmo/simplejwt/releases/tag/v1.1.1 | |
| https://github.com/kelvinmo/simplejwt/security/advisories/GHSA-xw36-67f8-339x |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-33204 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-33204
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-33204 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-33204 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Mar. 20, 2026
Action Type Old Value New Value Added Description 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. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added CWE CWE-400 Added Reference https://github.com/kelvinmo/simplejwt/releases/tag/v1.1.1 Added Reference https://github.com/kelvinmo/simplejwt/security/advisories/GHSA-xw36-67f8-339x