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GHSA-gcgp-q2jq-fw52
No affected components available
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.
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs high-level or administrative privileges. The attacker needs the user to perform some action, like clicking a link. The impact is confined to the system where the vulnerability exists. There is a low impact on the confidentiality of the information. There is a low impact on the integrity of the data.
Limited exploitation activity has been observed. Close monitoring and planned remediation are recommended.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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