---
id: CVE-2026-53599
title: REDAXO is a PHP-based content management system
summary: >-
  REDAXO is a PHP-based content management system. From 5.18.2 until 5.21.1,
  rex_mediapool::isAllowedExtension in
  redaxo/src/addons/mediapool/lib/mediapool.php lets an authenticated backend
  user with media[upload] permission upload a JPEG/…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-434
vendor: redaxo
product: redaxo/source
affected:
  - 'redaxo/source >= 5.18.2, < 5.21.1'
patched:
  - redaxo/source 5.21.1
published: '2026-07-31'
updated: '2026-09-09'
sourceUpdated: '2026-09-09T20:55:04.493'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-53599'
references:
  - url: >-
      https://github.com/redaxo/core/commit/462e36896bb65d292ba22d711044c23c9cfb0340
    label: security-advisories@github.com
  - url: 'https://github.com/redaxo/core/pull/6538'
    label: security-advisories@github.com
  - url: 'https://github.com/redaxo/core/releases/tag/5.21.1'
    label: security-advisories@github.com
  - url: 'https://github.com/redaxo/core/security/advisories/GHSA-98pp-vccm-qm25'
    label: security-advisories@github.com
  - url: 'https://github.com/redaxo/core/security/advisories/GHSA-98pp-vccm-qm25'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: 'https://github.com/advisories/GHSA-98pp-vccm-qm25'
tags:
  - nvd
  - ghsa
  - composer
epss: 0.00395
epssPercentile: 0.33567
aliases:
  - GHSA-98pp-vccm-qm25
ecosystem: composer
ingestedAt: '2026-07-31T20:02:42.843Z'
---

## Overview

REDAXO is a PHP-based content management system. From 5.18.2 until 5.21.1, rex_mediapool::isAllowedExtension in redaxo/src/addons/mediapool/lib/mediapool.php lets an authenticated backend user with media[upload] permission upload a JPEG/PHP polyglot named shell.php.any.jpg, which web servers with multi-extension PHP handlers can execute as the web-server user. This issue is fixed in version 5.21.1.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-53599)

Affected packages:

- `redaxo/source >= 5.18.2, < 5.21.1`

Patched in:

- `redaxo/source 5.21.1`

Source: https://github.com/advisories/GHSA-98pp-vccm-qm25