CVE-2021-3277: Nagios XI

High severity, CVSS 7.2. EPSS: 54.6% chance of exploitation in the next 30 days.

Nagios XI 5.7.5 and earlier allows authenticated admins to upload arbitrary files due to improper validation of the rename functionality in custom-includes component, which leads to remote code execution by uploading php files.

Affected products

• Nagios Nagios XI: up to and including 5.7.5

Published 2021-06-07. Last modified 2026-06-17.