CVE-2026-45694: LibreNMS: Reflected XSS via Proxmox instance/vmid GET parameters injected into document.title JavaScript assignment

August 12, 2026

LegacyController.php:75 writes the page title into a document.title JS assignment using string interpolation. apps/proxmox.inc.php pushes $vars['instance'] and $vars['vmid'] (GET params, only strip_tags() applied) directly into $pagetitle. A single quote terminates the JS string, executing arbitrary script.

References

github.com/advisories/GHSA-jmqm-f8q4-v7wx
github.com/librenms/librenms/releases/tag/26.5.0
github.com/librenms/librenms/security/advisories/GHSA-jmqm-f8q4-v7wx
nvd.nist.gov/vuln/detail/CVE-2026-45694

Code Behaviors & Features

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