Summary

The Oxidized integration URL (oxidized.url) is admin-configurable. LibreNMS fetches device info and version history from that URL and renders JSON fields (name, ip, model, author, commit message) into HTML without htmlspecialchars(). An admin pointing the URL at an attacker-controlled server achieves persistent XSS affecting all users who view any device's showconfig tab.

CVSS

CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:N — 8.1 High

Details

// includes/html/pages/device/showconfig.inc.php:276-278
echo '<li ...><strong>Node:</strong> ' . $node_info['name'] . '</li>';
echo '<li ...><strong>IP:</strong> '   . $node_info['ip']   . '</li>';
echo '<li ...><strong>Model:</strong> '. $node_info['model'] . '</li>';
// lines 349, 353: author and commit message also unescaped

Attack chain

1. Admin sets oxidized.url to http://attacker.example.com/.
2. Attacker server returns {"name":"<img src=x onerror=alert(1)>","ip":"x","model":"x"}.
3. Any user viewing any device showconfig tab triggers the XSS.

PoC

Mock Oxidized server confirmed in response:

[!!!] CONFIRMED — ...<strong>Node:</strong> <img src=x onerror="alert('SSRF-XSS-oxidized')">...

Fix

echo '<li ...><strong>Node:</strong> ' . htmlspecialchars($node_info['name'], ENT_QUOTES, 'UTF-8') . '</li>';

Apply to all fields from $node_info, $author, $msg.

Prerequisite

Admin session. Oxidized integration must be enabled.

References

• GHSA-7gww-x7fh-jf9j
• https://github.com/librenms/librenms/releases/tag/26.7.0