LibreNMS is vulnerable to Reflected-XSS in `report_this` function

Summary

Reflected-XSS in report_this function in librenms/includes/functions.php

Details

Recently, it was discovered that the report_this function had improper filtering (htmlentities function was incorrectly used in a href environment), which caused the project_issues parameter to trigger an XSS vulnerability.

The Vulnerable Sink: https://github.com/librenms/librenms/blob/master/includes/functions.php#L444

PoC

GET project_issues=javascript:alert(document.cookie)

Impact

XSS vulnerabilities allow attackers to execute malicious scripts in users' browsers, enabling unauthorized access to sensitive data, session hijacking, or malware distribution.

Suggestion

It is recommended to filter dangerous protocols, e.g. javascript:/file:.