XSS in Nagios Enterprises, Llc. Core
CVE-2026-48550
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.
Vulnerability class: XSS (Cross-Site Scripting)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.
EPSS exploit prediction
EPSS: 0.004 (35.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 36th percentile — 35.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.004 · change: +0.002
Affected products
- Nagios Enterprises, Llc. Core — versions 0
- Nagios Enterprises, Llc. Xi — versions 0
Weakness classification (CWE)
References
- www.nagios.com/security-disclosures/nagios-core/ (vendor-advisory, patch)
- github.com/NagiosEnterprises/nagioscore/blob/master/Changelog (release-notes)
- www.vulncheck.com/advisories/nagios-core-xi-cmd-cgi-reflected-xss-via-nagformid… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-48550?
- CVE-2026-48550 is a medium-severity vulnerability in Nagios Enterprises, Llc. Core, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-08-12.
- How severe is CVE-2026-48550?
- Medium severity. CVSS v3 base score is 6.1 out of 10.