GHSA-gcgp-q2jq-fw52 is a low-severity (CVSS 3.5) Cross-site Scripting (XSS) vulnerability in librenms/librenms. 1 public exploit reference exists, so weaponization risk is real. A fix is available for librenms/librenms — see the affected versions and patch details below.
LibreNMS has Stored Cross-site Scripting vulnerability in "Alert Templates" feature
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-gcgp-q2jq-fw52.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-gcgp-q2jq-fw52 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,166 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
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 Self Cross-Site Scripting (Self-XSS) vulnerability in the "Alert Templates" feature allows users to inject arbitrary JavaScript into the alert template's name. This script executes immediately upon submission but does not persist after a page refresh.
Details
The vulnerability occurs when creating an alert template in the LibreNMS interface. Although the application sanitizes the "name" field when storing it in the database, this newly created template is immediately added to the table without any sanitization being applied to the name, allowing users to inject arbitrary JavaScript. This script executes when the template is created but does not persist in the database, thus preventing stored XSS.
For instance, the following payload can be used to exploit the vulnerability:
test1<script>{onerror=alert}throw 1337</script>
The root cause of this vulnerability lies in the lack of sanitization of the "name" variable before it is rendered in the table. The vulnerability exists because the bootgrid function of the jQuery grid plugin does not sanitize the text being added to the table. Although tags are stripped before being added to the database (as shown in the code below), the vulnerability still allows Self-XSS during the creation of the template.
Where the variable is being sanitized before being stored in the database: https://github.com/librenms/librenms/blob/0e741e365aa974a74aee6b43d1b4b759158a5c7e/includes/html/forms/alert-templates.inc.php#L40
Where the vulnerability is happening: https://github.com/librenms/librenms/blob/0e741e365aa974a74aee6b43d1b4b759158a5c7e/includes/html/modal/alert_template.inc.php#L205
PoC
- Navigate to the "Alert Templates" creation page in the LibreNMS interface.
- In the "Name" field, input the following payload:
test1<script>{onerror=alert}throw 1337</script> - Submit the form to create the alert template.
- Observe that the JavaScript executes immediately, triggering an alert popup. However, this code does not persist after refreshing the page.
Impact
This is a Self Cross-Site Scripting (Self-XSS) vulnerability. Although the risk is lower compared to traditional XSS, it can still be exploited through social engineering or tricking users into entering or interacting with malicious code. This can lead to unauthorized actions or data exposure in the context of the affected user's session.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | librenms/librenms | all versions | 24.9.0composer require librenms/librenms:^24.9.0 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & 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 24.9.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-gcgp-q2jq-fw52 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-gcgp-q2jq-fw52 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-gcgp-q2jq-fw52. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-gcgp-q2jq-fw52 in your dependencies?
O3 Security finds GHSA-gcgp-q2jq-fw52 across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.