High severityNVD Advisory· Published Jul 31, 2026· Updated Jul 31, 2026
Redaxo has a Mediapool isAllowedExtension bypass via multi-segment filename that leads to authenticated RCE on Apache mod_php multi-extension handlers
CVE-2026-53599
Description
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.
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Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
redaxo/sourcePackagist | >= 5.18.2, < 5.21.1 | 5.21.1 |
Affected products
1Patches
Vulnerability mechanics
References
5- github.com/advisories/GHSA-98pp-vccm-qm25ghsaADVISORY
- github.com/redaxo/core/commit/462e36896bb65d292ba22d711044c23c9cfb0340ghsax_refsource_MISCWEB
- github.com/redaxo/core/pull/6538ghsax_refsource_MISCWEB
- github.com/redaxo/core/releases/tag/5.21.1ghsax_refsource_MISCWEB
- github.com/redaxo/core/security/advisories/GHSA-98pp-vccm-qm25ghsax_refsource_CONFIRMWEB
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