GHSA-c66p-64fj-jmc2 is a medium-severity (CVSS 4.6) Cross-site Scripting (XSS) vulnerability in librenms/librenms. EPSS puts its 30-day exploitation probability at 30.9% (98th percentile). A fix is available for librenms/librenms — see the affected versions and patch details below.
LibreNMS Misc Section Stored Cross-site Scripting vulnerability
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-c66p-64fj-jmc2.
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-c66p-64fj-jmc2 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 378,156 CVEs with a current EPSS score, this one falls in the 10–50% 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
StoredXSS-LibreNMS-MiscSection
Description:
Stored XSS on the parameter: ajax_form.php -> param: state
Request:
POST /ajax_form.php HTTP/1.1
Host: <your_host>
X-Requested-With: XMLHttpRequest
X-CSRF-TOKEN: <your_XSRF_token>
Content-Type: application/x-www-form-urlencoded; charset=UTF-8
Cookie: <your_cookie>
type=override-config&device_id=1&attrib=override_icmp_disable&state="><img%20src%20onerror="alert(1)">
of Librenms version 24.10.1 (https://github.com/librenms/librenms) allows remote attackers to inject malicious scripts. When a user views or interacts with the page displaying the data, the malicious script executes immediately, leading to potential unauthorized actions or data exposure.
The vulnerability in the line:
$attrib_val = get_dev_attrib($device, $name);
within the dynamic_override_config function arises because the value of $attrib_val is retrieved from untrusted data without any sanitization or encoding (at Line 778).
When dynamic_override_config is called, the unescaped $attrib_val is injected directly into the HTML (at misc.inc.php).
Proof of Concept:
- Add a new device through the LibreNMS interface.
- Edit the newly created device and select the Misc section.
- In any of the following fields: "Override default ssh port", "Override default telnet port", "Override default http port" or "Unix agent port", enter the payload:
"><img src onerror="alert(document.cookie)">. - Save the changes.
- Observe that when the page loads, the XSS payload executes, triggering a popup that displays the current cookies.
Impact:
Execution of Malicious Code
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | librenms/librenms | ≥ 23.9.0&&< 24.11.0 | 24.11.0composer require librenms/librenms:^24.11.0 |
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 24.11.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-c66p-64fj-jmc2 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-c66p-64fj-jmc2 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-c66p-64fj-jmc2. 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-c66p-64fj-jmc2 in your dependencies?
O3 Security finds GHSA-c66p-64fj-jmc2 across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.