medium CVSS 6.1

CVE-2025-66026·PHP vulnerability

REDAXO is a PHP-based CMS. Prior to version 5.20.1, a reflected Cross-Site Scripting (XSS) vulnerability exists in the Mediapool view where the request parameter args[types] is rendered into an info banner without HTML-escaping. This allows arbitrary JavaScript execution in the backend context when an authenticated user visits a crafted link while logged in. This issue has been patched in version 5.20.1.

Severity
medium
Software
PHP
Fixed in
5.20.1
Published
2025-11-26

Affected versions

Until: 5.20.1

Fixed in: 5.20.1

How to fix this CVE

REDAXO CMS users must upgrade to version 5.20.1 or later to patch a reflected XSS vulnerability in the Mediapool component. The vulnerability allows authenticated attackers to inject malicious scripts through a crafted URL parameter that bypasses HTML encoding. Ensure all backend users are notified to upgrade immediately and avoid clicking untrusted links while logged into the REDAXO admin panel.

sudo dnf update php

Defensia detects this vulnerability

What an exploitation attempt looks like

Sample log line indicative of exploitation attempts:

GET|POST request to admin interface with parameter pattern `args\[types\]=[^&]*<script|args\[types\]=[^&]*javascript:|args\[types\]=[^&]*onerror=|args\[types\]=[^&]*onload=` targeting /index.php?page=mediapool or similar Mediapool paths

WAF mitigation (if patching is not yet possible)

Add this rule to your WAF to block exploitation attempts while you schedule the patch. 

Block or sanitize requests containing unescaped HTML/JavaScript in the args[types] query parameter by implementing input validation rules that reject angle brackets, event handlers (onerror, onload, onclick), and script tags in this parameter. Apply strict output encoding for any data reflected in admin panel info banners.

How to check if you are affected

  1. Step 1: Check REDAXO version with `grep -r "version" /path/to/redaxo/redaxo/src/core/boot.php | grep -oP '\d+\.\d+\.\d+'` or verify in admin dashboard under System → About
  2. Step 2: Search for the Mediapool module accessibility by reviewing /redaxo/src/addons/mediapool/ directory permissions and admin user access logs
  3. Step 3: Check web server logs (Apache/Nginx) for GET/POST requests containing `args[types]=` parameter in URLs targeting `/index.php?page=mediapool` or similar admin paths
  4. Step 4: Verify REDAXO version is 5.20.1 or higher by running `grep -r '5\.20\.[1-9]' /path/to/redaxo/` or checking the official GitHub releases page

FAQ

What is CVE-2025-66026?

CVE-2025-66026 is a reflected XSS vulnerability in REDAXO CMS versions prior to 5.20.1 affecting the Mediapool admin interface. An attacker can craft a malicious URL with unescaped HTML in the args[types] parameter to execute arbitrary JavaScript in the context of an authenticated backend user.

Is CVE-2025-66026 being actively exploited?

No, this vulnerability is not currently listed on the CISA KEV catalog and no public exploits are available as of this writing.

What versions of REDAXO are affected by CVE-2025-66026?

All REDAXO versions up to and including 5.20.0 are vulnerable; the issue is resolved in version 5.20.1 and later.

How do I check if my server is vulnerable to CVE-2025-66026?

Run `grep -r 'version' /path/to/redaxo/redaxo/src/core/boot.php` to extract the installed version and compare it against 5.20.1. If your version is below 5.20.1, you are vulnerable.

Does Defensia detect CVE-2025-66026?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If REDAXO is installed on a monitored server, CVE-2025-66026 will appear in your dashboard with remediation steps.

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References

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