CVE-2026-45694 LibreNMS: Reflected XSS in the Proxmox app view via unsanitized instance/vmid parameters
Reflected XSS in LibreNMS allows attackers to execute scripts in authenticated users' sessions via crafted links, potentially stealing session data.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-45694?
CVE-2026-45694 is a medium-severity cross-site scripting vulnerability in librenms, published on 26 Aug 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
LibreNMS is a network monitoring system. In versions up to and including 26.4.0, the Proxmox application view is vulnerable to reflected cross-site scripting through the user-supplied instance and vmid GET parameters, which are reflected into the page title without adequate encoding. The parameters are placed into the page title with only strip_tags applied, and the title is then written into an inline document.title assignment through string interpolation, so a single quote terminates the JavaScript string and the remaining input runs as script. An attacker who lures an authenticated user into following a crafted link can execute script in that user's session, enabling actions such as theft of session data. This issue is fixed in version 26.5.0.
Weakness: CWE-79
Which versions are affected by CVE-2026-45694?
2 open source packages ship an affected version, including librenms/librenms.
| Package | Affected | Fixed in |
|---|---|---|
librenms/librenms Packagist | All versions | 26.5.0 |
librenms/librenms Packagist | All versions | 26.5.0 |
How do I fix CVE-2026-45694?
Upgrade librenms/librenms to 26.5.0 or later.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-45694 being exploited?
There is no known exploitation of CVE-2026-45694 in the wild and no public exploit code.
Sources
Also known as GHSA-jmqm-f8q4-v7wx.