Summary
REDAXO: Stored XSS in Mediapool Sync Page via Unescaped Filesystem Filenames
The mediapool sync page (sync.php) renders filenames from the /media filesystem directory directly into HTML without applying rex_escape() (i.e., htmlspecialchars). Any file placed in the media directory whose filename contains HTML metacharacters will execute JavaScript in the browser of any backend user who views the sync page.
Details
In redaxo/src/addons/mediapool/pages/sync.php, the variable $diffFiles is populated from actual filesystem filenames (files in /media/ not yet registered in the database). These filenames are then rendered without escaping:
File: redaxo/src/addons/mediapool/pages/sync.php:119-120
foreach ($diffFiles as $file) {
if (is_writable(rex_path::media($file))) {
$e = [];
$e['label'] = '<label>' . $file . '</label>'; // NO rex_escape!
$e['field'] = '<input type="checkbox" name="sync_files[]" value="' . $file . '" />'; // NO rex_escape!
$writable[] = $e;
} else {
$notWritable[] = $file;
}
}
File: redaxo/src/addons/mediapool/pages/sync.php:170
$fragment->setVar('body', '<ul><li>' . implode('</li><li>', $notWritable) . '</li></ul>', false);
// $notWritable contains unescaped filenames
By contrast, all other filename displays in the codebase use rex_escape($fname) (e.g., media.detail.php:236, media.list.php). The sync page is accessible to any backend user with the media[sync] permission (not exclusively admins).
PoC
- Place a file named
<img src=x onerror=alert(document.cookie)>.txtinto the REDAXO/media/directory (via backup restore or server access) without adding it to the media database. - Log in as any backend user with
media[sync]permission. - Navigate to Mediapool → Sync.
- The XSS payload executes immediately, stealing the admin session cookie.
Impact
Stored XSS in the admin panel. An attacker who can place files in the media directory (via admin-level backup restore or server access) can achieve persistent XSS against all users who visit the sync page, including higher-privileged admins. This enables session hijacking, credential theft, and full CMS takeover.
Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.
CVE-2026-63002 has a CVSS score of 4.8 (Medium). The vector is network-reachable, high privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (5.21.2); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Already deployed Kodem?
See it in your environmentNew to Kodem? Get a demo →Remediation advice
Apply rex_escape() to all filename variables before inserting into HTML:
$e['label'] = '<label>' . rex_escape($file) . '</label>';
$e['field'] = '<input type="checkbox" name="sync_files[]" value="' . rex_escape($file) . '" />';
// ...
$fragment->setVar('body', '<ul><li>' . implode('</li><li>', array_map('rex_escape', $notWritable)) . '</li></ul>', false);
Frequently Asked Questions
- What is CVE-2026-63002? CVE-2026-63002 is a medium-severity cross-site scripting (XSS) vulnerability in redaxo/source (composer), affecting versions <= 5.21.1. It is fixed in 5.21.2. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
- How severe is CVE-2026-63002? CVE-2026-63002 has a CVSS score of 4.8 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of redaxo/source are affected by CVE-2026-63002? redaxo/source (composer) versions <= 5.21.1 is affected.
- Is there a fix for CVE-2026-63002? Yes. CVE-2026-63002 is fixed in 5.21.2. Upgrade to this version or later.
- Is CVE-2026-63002 exploitable, and should I be worried? Whether CVE-2026-63002 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-63002 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-63002? Upgrade
redaxo/sourceto 5.21.2 or later.