CVE-2026-48549 Nagios Core / XI CSRF via cmd.cgi Double-Submit Cookie
Attackers can bypass CSRF protections in Nagios Core and XI to execute commands as authenticated users, requiring an upgrade to patched versions.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-48549?
CVE-2026-48549 is a medium-severity vulnerability in Nagios Core, published on 26 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
Nagios Core before 4.5.13 and Nagios XI before 2026R1.5 contains a CSRF vulnerability in cmd.cgi. When no Cookie header is present, the double-submit cookie protection can be bypassed by supplying matching NagFormId and nagFormId values in the POST body, allowing a cross-site request to execute Nagios commands as a currently authenticated user.
Weakness: CWE-352
Which versions are affected by CVE-2026-48549?
How do I fix CVE-2026-48549?
Upgrade to a fixed version.
Is CVE-2026-48549 being exploited?
There is no known exploitation of CVE-2026-48549 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-48549, GHSA-xm5q-p2r5-r5wj, UBUNTU-CVE-2026-48549.