Description
Nagios Core before 4.5.14 and Nagios XI before 2026R1.7 are vulnerable to reflected cross-site scripting in cmd.cgi via the NagFormId parameter. An unauthenticated remote attacker can craft a malicious link that, when followed by an authenticated user, executes arbitrary JavaScript in the victim's browser.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Nagios Enterprises, LLC. | Nagios Core | < 4.5.14 | 4.5.14 |
| Nagios Enterprises, LLC. | Nagios XI | < 2026R1.7 | 2026R1.7 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | nagios4 | 4.5.14+ds-1 | — |
| Debian 13 | nagios4 | 4.4.6-4.1+deb13u2 | — |
| Debian 12 | nagios4 | 4.4.6-4+deb12u2 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | nagios4 | No fix yet | — |
| Ubuntu 26.04 LTS | nagios4 | No fix yet | — |
| Ubuntu 24.04 LTS | nagios4 | No fix yet | — |
| Ubuntu 22.04 LTS | nagios4 | No fix yet | — |
| Ubuntu 20.04 LTS | nagios4 | No fix yet | — |
Advisories 1
- WID-SEC-2026-2819 Nagios Core und Nagios XI: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 12, 2026
References
- Security Disclosures vendor-advisory patch
- Changelog release-notes
- https://www.vulncheck.com/advisories/nagios-core-xi-cmd-cgi-reflected-xss-via-nagformid-parameter third-party-advisory