CVE-2025-55296

A stored Cross-Site Scripting (XSS) vulnerability exists in LibreNMS (<= 25.6.0) in the Alert Template creation feature. This allows a user with the admin role to inject malicious JavaScript, which will be executed when the template is rendered, potentially compromising other admin accounts.

Details

In the LibreNMS web UI, when a user with the admin role visits /templates and clicks "Create new alert template", the "Template name" field fails to properly sanitize input. By inserting a payload like:

<script>alert(document.cookie)</script> 

and filling the other fields with arbitrary content (e.g., test), once the template is saved, the script is executed. This confirms that user input is stored and later rendered without proper output encoding.

This vulnerability can be exploited for session hijacking, data theft, or other malicious actions targeting other admin users.

PoC

1. Log in to LibreNMS using an account with the admin role.

2. Navigate to: http://localhost:8000/templates.

3. Click the "Create new alert template" button.

4. Input the following into the Template name field:

   <script>alert(document.cookie)</script>
   

5. Fill the remaining fields (Template, Alert title, Recovery title) with arbitrary content such as test.

6. Click "Create template".

7. Upon saving, a JavaScript alert pops up, confirming the stored XSS is triggered.

Type: Stored Cross-Site Scripting (XSS)
Affected users: Only accounts with the admin role who access the Alert Templates page (http://localhost:8000/templates) are affected.
Attackers need: Authenticated admin-level access.

Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.

CVE-2025-55296 has a CVSS score of 5.5 (Medium). The vector is network-reachable, high privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (25.8.0); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2025-55296? CVE-2025-55296 is a medium-severity cross-site scripting (XSS) vulnerability in librenms/librenms (composer), affecting versions < 25.8.0. It is fixed in 25.8.0. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. How severe is CVE-2025-55296? CVE-2025-55296 has a CVSS score of 5.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of librenms/librenms are affected by CVE-2025-55296? librenms/librenms (composer) versions < 25.8.0 is affected.
4. Is there a fix for CVE-2025-55296? Yes. CVE-2025-55296 is fixed in 25.8.0. Upgrade to this version or later.
5. Is CVE-2025-55296 exploitable, and should I be worried? Whether CVE-2025-55296 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2025-55296 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2025-55296? Upgrade librenms/librenms to 25.8.0 or later.