CVE-2026-48548: Nagios Core CSRF via cmd.cgi

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-26 · updated 2026-09-24
Weakness: CWE-352

Description

Nagios Core before 4.5.12 contains a cross-site request forgery vulnerability in cmd.cgi where the CSRF protection mechanism passes validation when the NagFormId cookie is absent. Attackers can craft a malicious cross-site POST request to execute arbitrary Nagios commands as a currently authenticated user without their knowledge or consent.

Affected products

Nagios Enterprises, LLC. Nagios Core: before 4.5.12 — fixed in 4.5.12

How to fix

Upgrade to a fixed version: Nagios Enterprises, LLC. Nagios Core 4.5.12. Check the vendor advisory for mitigations.

References

https://github.com/NagiosEnterprises/nagioscore/blob/master/Changelog
https://www.nagios.com/security-disclosures/nagios-core/
https://www.vulncheck.com/advisories/nagios-core-csrf-via-cmd-cgi

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