CVE-2026-53599: CWE-434: Unrestricted Upload of File with Dangerous Type in redaxo core
A vulnerability in REDAXO core versions from 5.18.2 up to but not including 5.21.1 allows an authenticated backend user with media upload permissions to upload a specially crafted file with multiple extensions. This file can be executed by web servers configured to process multi-extension PHP files, potentially leading to remote code execution. The issue is fixed in version 5.21.1.
AI Analysis
Technical Summary
CVE-2026-53599 is an unrestricted file upload vulnerability in the REDAXO CMS core affecting versions >=5.18.2 and <5.21.1. The function rex_mediapool::isAllowedExtension improperly validates file extensions, allowing an authenticated backend user with media[upload] permission to upload a JPEG/PHP polyglot file named shell.php.any.jpg. Web servers configured to execute PHP code based on multiple file extensions may execute this uploaded file as PHP code, leading to full compromise of the web server process. The vulnerability is classified under CWE-434 (Unrestricted Upload of File with Dangerous Type). The issue is resolved in REDAXO version 5.21.1.
Potential Impact
An authenticated backend user with media upload permissions can upload a malicious file that may be executed by the web server, resulting in remote code execution with the privileges of the web server user. This can lead to complete compromise of the affected system, including confidentiality, integrity, and availability impacts.
Mitigation Recommendations
This vulnerability is fixed in REDAXO core version 5.21.1. Users should upgrade to version 5.21.1 or later to remediate this issue. No other official remediation or temporary fix is documented. Until upgrading, restrict backend user permissions to trusted users only and consider web server configuration changes to prevent execution of files with multiple extensions if possible.
CVE-2026-53599: CWE-434: Unrestricted Upload of File with Dangerous Type in redaxo core
Description
A vulnerability in REDAXO core versions from 5.18.2 up to but not including 5.21.1 allows an authenticated backend user with media upload permissions to upload a specially crafted file with multiple extensions. This file can be executed by web servers configured to process multi-extension PHP files, potentially leading to remote code execution. The issue is fixed in version 5.21.1.
CVSS v3.1
Score 7.5high
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-53599 is an unrestricted file upload vulnerability in the REDAXO CMS core affecting versions >=5.18.2 and <5.21.1. The function rex_mediapool::isAllowedExtension improperly validates file extensions, allowing an authenticated backend user with media[upload] permission to upload a JPEG/PHP polyglot file named shell.php.any.jpg. Web servers configured to execute PHP code based on multiple file extensions may execute this uploaded file as PHP code, leading to full compromise of the web server process. The vulnerability is classified under CWE-434 (Unrestricted Upload of File with Dangerous Type). The issue is resolved in REDAXO version 5.21.1.
Potential Impact
An authenticated backend user with media upload permissions can upload a malicious file that may be executed by the web server, resulting in remote code execution with the privileges of the web server user. This can lead to complete compromise of the affected system, including confidentiality, integrity, and availability impacts.
Mitigation Recommendations
This vulnerability is fixed in REDAXO core version 5.21.1. Users should upgrade to version 5.21.1 or later to remediate this issue. No other official remediation or temporary fix is documented. Until upgrading, restrict backend user permissions to trusted users only and consider web server configuration changes to prevent execution of files with multiple extensions if possible.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-06-09T19:39:52.404Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a6cfc17bf32cb7a343268a6
Added to database: 07/31/2026, 19:48:39 UTC
Last enriched: 07/31/2026, 20:03:03 UTC
Last updated: 07/31/2026, 20:03:03 UTC
Views: 4
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