high CVSS 7.5

CVE-2024-47523·PHP vulnerability

LibreNMS is an open-source, PHP/MySQL/SNMP-based network monitoring system. 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. This vulnerability is fixed in 24.9.0.

Severity
high
Software
PHP
Fixed in
24.9.0
Published
2024-10-01

Affected versions

Until: 24.9.0

Fixed in: 24.9.0

How to fix this CVE

LibreNMS administrators must upgrade to version 24.9.0 or later to patch a stored XSS vulnerability in the Alert Transports feature that allows authenticated users to inject malicious scripts through transport configuration fields. The vulnerability can be exploited to execute arbitrary JavaScript in other users' browsers, potentially leading to account compromise. Apply the update immediately to all affected LibreNMS instances.

sudo dnf upgrade php

Defensia detects this vulnerability

What an exploitation attempt looks like

Sample log line indicative of exploitation attempts:

POST /librenms/includes/html/print-alert-transports.php with parameters containing script tags, javascript: protocol, or event handlers (e.g., onerror=, onclick=) in the Details or transport configuration fields; log pattern: POST.*print-alert-transports\.php.*\b(script|javascript:|on\w+\s*=)

WAF mitigation (if patching is not yet possible)

Add this rule to your WAF to block exploitation attempts while you schedule the patch. 

Configure WAF rules to block POST requests to print-alert-transports.php containing JavaScript event handlers or script tags in request body parameters; implement Content Security Policy (CSP) headers with script-src 'self' to prevent inline script execution; sanitize all user input in transport detail fields server-side using HTML entity encoding before storage and display.

How to check if you are affected

  1. Check LibreNMS version: curl -s http://localhost/librenms/ | grep -i 'version' or check the .git/config if running from source
  2. Verify if Alert Transports feature is in use: Log into LibreNMS admin panel and navigate to Alerts → Alert Transports to see if any transports are configured
  3. Search web server logs for suspicious POST requests to print-alert-transports.php: grep -r 'print-alert-transports.php' /var/log/apache2/ /var/log/nginx/ containing encoded script tags or javascript: protocol
  4. Confirm the patch by checking the commit hash in the LibreNMS installation: git log --oneline | grep ee1afba or verify version string shows 24.9.0+

FAQ

What is CVE-2024-47523?

This is a stored cross-site scripting (XSS) flaw in LibreNMS's Alert Transports configuration interface that permits authenticated users to embed malicious JavaScript code in transport detail fields, which executes when other administrators view the affected transport settings.

Is CVE-2024-47523 being actively exploited?

No, this vulnerability is not currently listed in the CISA Known Exploited Vulnerabilities (KEV) catalog and no public exploits are available, though the vulnerability should still be patched promptly due to its high severity score and account compromise potential.

What versions of LibreNMS are affected by CVE-2024-47523?

All versions prior to LibreNMS 24.9.0 are vulnerable; the exact earliest affected version is unknown but the vulnerability affects the Alert Transports feature across the codebase history.

How do I check if my server is vulnerable to CVE-2024-47523?

Run `curl -s http://your-librenms-host/librenms/ | grep -oP '(?<=Version\s)[\d.]+' | head -1` to retrieve your current version; if it is below 24.9.0, your system is vulnerable.

Does Defensia detect CVE-2024-47523?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If LibreNMS is installed on a monitored server, CVE-2024-47523 will appear in your dashboard with remediation steps.

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References

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