High severity · published Jul 31, 2026
CVE-2026-53599
Redaxo has a Mediapool isAllowedExtension bypass via multi-segment filename that leads to authenticated RCE on Apache mod_php multi-extension handlers
7.5
CVSS
0.5%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
High
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 43% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CO
core · redaxo
>= 5.18.2, < 5.21.1 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-53599
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-53599
github.com
https://github.com/redaxo/core/commit/462e36896bb65d292ba22d711044c23c9cfb0340
github.com
https://github.com/redaxo/core/pull/6538
github.com
https://github.com/redaxo/core/releases/tag/5.21.1
github.com
https://github.com/redaxo/core/security/advisories/GHSA-98pp-vccm-qm25
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