CVE-2024-47523

A Stored Cross-Site Scripting (XSS) vulnerability in the "Alert Transports" feature allows authenticated users to inject arbitrary JavaScript through the "Details" section (which contains multiple fields depending on which transport is selected at that moment). This vulnerability can lead to the execution of malicious code in the context of other users' sessions, potentially compromising their accounts and allowing unauthorized actions.

Details

The vulnerability occurs when creating an alert transport. The application does not properly sanitize the user input in the "Details" field, allowing an attacker to inject and store arbitrary JavaScript. This script is then executed in the context of the page whenever the alert transport is viewed or processed.

For instance, the following payload can be used to trigger the XSS:
test1<script>{onerror=alert}throw 1337</script>

When the page containing the transport details is loaded, this payload causes the browser to execute the injected script, which in this case triggers an alert popup.

The root cause of the vulnerability is that the application does not sanitize the value of $instance->displayDetails before appending it to the HTML output. This is demonstrated in the following code:
https://github.com/librenms/librenms/blob/4777247327c793ed0a3306d0464b95176008177b/includes/html/print-alert-transports.php#L40

PoC

1. Create a new alert transport in the LibreNMS interface.
2. Depending on the transport chosen, just input the following payload in any field that ends up in the "Details" section:

test1<script>{onerror=alert}throw 1337</script>
3. Save the transport and trigger the alert.
4. When the transport details are accessed, the injected script executes, displaying an alert popup.

Example 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>

_token=<your_token>&transport_id=2&type=alert-transports&name=Test1&transport-choice=canopsis-form&_token=Ep6belaqXe5qE301CGmtoOWJ71gvRfBXjRyhXEpH&transport-type=canopsis&canopsis-host=localhost%3Cscript%3E%7Bonerror%3Dalert%7Dthrow+1337%3C%2Fscript%3E&canopsis-port=5000&canopsis-user=%3Cscript%3E%7Bonerror%3Dalert%7Dthrow+1337%3C%2Fscript%3E&canopsis-pass=%3Cscript%3E%7Bonerror%3Dalert%7Dthrow+1337%3C%2Fscript%3E&canopsis-vhost=%3Cscript%3E%7Bonerror%3Dalert%7Dthrow+1337%3C%2Fscript%3E

It could allow authenticated users to execute arbitrary JavaScript code in the context of other users' sessions. Impacted users could have their accounts compromised, enabling the attacker to perform unauthorized actions on their behalf.

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-2024-47523 has a CVSS score of 7.5 (Medium). The vector is network-reachable, high privileges required, and user interaction required. 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 (24.9.0); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2024-47523? CVE-2024-47523 is a medium-severity cross-site scripting (XSS) vulnerability in librenms/librenms (composer), affecting versions < 24.9.0. It is fixed in 24.9.0. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. How severe is CVE-2024-47523? CVE-2024-47523 has a CVSS score of 7.5 (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-2024-47523? librenms/librenms (composer) versions < 24.9.0 is affected.
4. Is there a fix for CVE-2024-47523? Yes. CVE-2024-47523 is fixed in 24.9.0. Upgrade to this version or later.
5. Is CVE-2024-47523 exploitable, and should I be worried? Whether CVE-2024-47523 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-2024-47523 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-2024-47523? Upgrade librenms/librenms to 24.9.0 or later.