GHSA-5gm9-622f-qcg5 — librenms/librenms
LOWGHSA-5gm9-622f-qcg5 is a low-severity (CVSS 3.5) Cross-site Scripting (XSS) vulnerability in librenms/librenms. A fix is available for librenms/librenms — see the affected versions and patch details below.
LibreNMS: Cross-Site Scripting in ShowConfigController
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for GHSA-5gm9-622f-qcg5.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
GHSA-5gm9-622f-qcg5 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 380,526 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
librenms/librenmsReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
Summary
A Stored Cross-Site Scripting (XSS) vulnerability exists in the ShowConfig page of devices affected by the RANCID Integration settings. The application fails to properly sanitise the rancid_repo_url configuration value. When a user navigates to a device's configuration page, this unsanitised value is rendered directly within an HTML anchor (<a>) tag. This allows an authenticated user with permission to modify external settings to inject malicious JavaScript that will execute in the browser of any user viewing the affected device pages.
Details
The vulnerability is located in the external settings configuration block, specifically at the settings/external/rancid endpoint. When a valid rancid_configs is set, the application renders the corresponding rancid_repo_url as a clickable link labeled "Git Repository" on the /device/{id}/showconfig UI.
Because the rancid_repo_url input is neither validated upon saving nor contextually encoded upon rendering, an attacker can break out of the href attribute context or use JavaScript URIs to attach malicious event handlers or scripts.
This vulnerability is introduced by the line 13 of https://github.com/librenms/librenms/blob/master/includes/html/pages/device/showconfig.inc.php.
PoC
-
Login as an admin and navigate to
<img width="790" height="155" alt="image" src="https://github.com/user-attachments/assets/348fff1b-dfce-4735-9273-055113695368" />/settings/external/rancid. -
Add a valid path to
rancid_configs. This can be any directory ended with.git. -
Put
<img width="909" height="276" alt="image" src="https://github.com/user-attachments/assets/b8c5d650-ba05-4326-8a2d-bea8defa7373" />"></a><img/src/onerror=alert(1)><a x="intorancid_repo_urlconfig. -
Navigate to a device page and click
Config(Or visit/device/{id}/showconfigdirectly). -
The XSS is triggered when visiting the page. It will pop up an alert dialog.
<img width="810" height="454" alt="image" src="https://github.com/user-attachments/assets/4d15784e-ff93-46ec-b13e-08a225a8d6d4" />
Other Payloads
javascript:alert(1)" x="- triggered by clicking the link.- ``" onmouseover="alert(1)" x="` - triggered by hovering on the link
Impact
Since an admin account is required to change the settings, the risk is minimal in systems with a single administrator. However, in environments with multiple administrative users, this constitutes an Admin-to-Admin Cross-Site Scripting attack. It could be used by a compromised admin account to execute arbitrary frontend code in the context of another administrator's session, potentially leading to session hijacking or unauthorized data exposure.
Remediation Advice
Ensure proper sanitisation is performed on affected fields, with all special characters escaped and HTML encoded. This can be done with existing frameworks like HTMLPurifier.
CVE Request
CVE References: https://projectblack.io/blog/librenms-authenticated-rce-and-xss/
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | librenms/librenms | ≥ 25.12.0&&< 26.3.0 | 26.3.0composer require librenms/librenms:^26.3.0 |
Affected Products
librenmslibrenmsDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for librenms/librenms, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update librenms/librenms to 26.3.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-5gm9-622f-qcg5 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.
Frequently Asked Questions
Is GHSA-5gm9-622f-qcg5 in your dependencies?
Find it across Packagist, including transitive dependencies.