PHP-Based Content Management System Vulnerability in REDAXO
CVE-2026-53599

7.5HIGH

Key Information:

Vendor

Redaxo

Status
Core
Vendor
CVE Published:
31 July 2026

What is CVE-2026-53599?

REDAXO, a PHP-based content management system, has a vulnerability that allows authenticated backend users with media upload permissions to upload potentially malicious files in the form of a JPEG/PHP polyglot named 'shell.php.any.jpg'. This file could be executed by web servers configured with multi-extension PHP handlers, enabling unauthorized access to the web server. The issue exists in versions 5.18.2 through 5.21.0 and has been addressed in version 5.21.1, which users are recommended to upgrade to in order to mitigate this risk.

Affected Version(s)

core >= 5.18.2, < 5.21.1

References

https://github.com/redaxo/core/security/advisories/GHSA-9...
x_refsource_CONFIRM
https://github.com/redaxo/core/pull/6538
x_refsource_MISC
https://github.com/redaxo/core/commit/462e36896bb65d292ba...
x_refsource_MISC

CVSS V3.1

Score:
7.5
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
High
Privileges Required:
Low
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.