CVE-2026-48550

Nagios Core / XI cmd.cgi Reflected XSS via NagFormId Parameter

5.1 MediumFix available

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.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: Active

What an attacker can affect

Confidentiality: None
Integrity: None
Availability: None

Exploit likelihood

0.44%Up 0.2 points since Aug 13, 2026

What each source reports

CVE List Score used 5.1

Nagios Core / XI cmd.cgi Reflected XSS via NagFormId Parameter

Record: CVE-2026-48550
CVSS 4.0: 5.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
CVSS 3.1: 6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Weakness: CWE-79
Updated: 2026-11-02

EUVDEUVD-2026-57324 5.1

Record: EUVD-2026-57324
CVSS 4.0: 5.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
Updated: 2026-11-02

GitHub AdvisoriesGHSA-hc96-98mh-7j3h 5.1

Nagios Core before 4.5.14 and Nagios XI before 2026R1.7 are vulnerable to reflected cross-site...

Record: GHSA-hc96-98mh-7j3h
CVSS 4.0: 5.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1: 6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Weakness: CWE-79
Updated: 2026-11-02

NVD 5.1

Record: CVE-2026-48550
CVSS 4.0: 5.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1: 6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Weakness: CWE-79
Updated: 2026-11-02

OSV 5.1

Nagios Core / XI cmd.cgi Reflected XSS via NagFormId Parameter

Record: CVE-2026-48550
CVSS 4.0: 5.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
Weakness: CWE-79
Updated: 2026-11-02

OSVDEBIAN-CVE-2026-48550 5.1

Record: DEBIAN-CVE-2026-48550
CVSS 4.0: 5.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Updated: 2026-11-02

OSVUBUNTU-CVE-2026-48550 5.1

Record: UBUNTU-CVE-2026-48550
CVSS 4.0: 5.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
CVSS 3.1: 6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Updated: 2026-11-02

Affected products

Affected packages

Affected packages
Package	Affected	Fixed
`nagios4` Debian:12	before 4.4.6-4+deb12u2, plus listed versions 4.4.6-44.4.6-4+deb12u1	4.4.6-4+deb12u2
`nagios4` Debian:13	before 4.4.6-4.1+deb13u2, plus listed versions 4.4.6-4.14.4.6-4.1+deb13u1	4.4.6-4.1+deb13u2
`nagios4` Debian:14	before 4.5.14+ds-1, plus listed versions 4.4.6-4.14.5.12+ds-1	4.5.14+ds-1
`nagios4` Ubuntu:20.04:LTS	All versions, plus listed versions 4.3.4-34.3.4-3ubuntu0.1	None known
`nagios4` Ubuntu:22.04:LTS	All versions, plus listed versions 4.4.6-44.4.6-4ubuntu0.22.04.1	None known
`nagios4` Ubuntu:24.04:LTS	All versions, plus listed versions 4.4.6-44.4.6-4ubuntu0.24.04.1	None known
`nagios4` Ubuntu:26.10	All versions, plus listed versions 4.4.6-4.1ubuntu2	None known
`nagios4` Ubuntu:26.04:LTS	All versions, plus listed versions 4.4.6-4.1ubuntu14.4.6-4.1ubuntu2	None known

History

History
Recorded	Changed	Sources
Nov 2, 2026	first indexed	CVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-48550 is a medium vulnerability (CVSS 5.1) in Nagios Enterprises Xi, published August 12, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.44%, the 38th percentile. Fixed in nagios4 4.4.6-4+deb12u2.