Executive brief
LibreNMS is an open-source network monitoring platform used by organizations to track and manage network devices and services. A vulnerability in the AboutController allows authenticated administrators to execute arbitrary code on the web server by modifying the snmpget configuration parameter to point to a malicious executable. Successful exploitation results in complete server compromise, enabling attackers to steal credentials, create backdoors, and disrupt monitoring operations.
Technical details
The vulnerability exists in LibreNMS's AboutController (app/Http/Controllers/AboutController.php line 85), where the snmpget configuration value is retrieved from the database and passed directly to shell_exec() without proper validation. While a sanitizePath() function attempts to block special characters (;, `, #, $, |, &, ', ", >, <, parentheses), it only prevents direct command injection and does NOT validate the destination of the executable path. An authenticated administrator can bypass this by modifying the snmpget configuration via the web interface (/settings/snmpget) to point to a pre-existing malicious executable on the system, then trigger execution by accessing the /about endpoint. The fix requires replacing shell_exec() with Symfony's Process component to properly separate command arguments from executable paths.
Affected products
- LibreNMS LibreNMS before 26.5.0
Timeline
- 2026-08-04: disclosed
- 2026-09-01: advisory
- 2026-09-01: patched: Version 26.5.0 released