CVE-2021-40344: Nagios XI

High severity, CVSS 7.2. EPSS: 64.8% chance of exploitation in the next 30 days.

An issue was discovered in Nagios XI 5.8.5. In the Custom Includes section of the Admin panel, an administrator can upload files with arbitrary extensions as long as the MIME type corresponds to an image. Therefore it is possible to upload a crafted PHP script to achieve remote command execution.

Affected products

• Nagios Nagios XI: version 5.8.5 only

Published 2021-10-26. Last modified 2026-06-17.