CVE-2026-48551

Nagios Core / XI CSRF Protection Bypass via Double-Submit Cookie

6.1 MediumFix available

Nagios Core before 4.5.14 and Nagios XI before 2026R1.7 contain a cross-site request forgery protection bypass via a self-supplied double-submit cookie. An attacker can supply matching cookie and request parameter values to bypass CSRF protection, enabling unauthenticated attackers to run commands as authorized users via malicious links.

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

0.26%Up 0.1 points since Aug 13, 2026

What each source reports

CVE List Score used 6.1

Nagios Core / XI CSRF Protection Bypass via Double-Submit Cookie

Record: CVE-2026-48551
CVSS 4.0: 6.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:N/SI:H/SA:N
CVSS 3.1: 7.4 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:H/A:N
Weakness: CWE-352
Updated: 2026-11-02

EUVDEUVD-2026-57326 6.1

Record: EUVD-2026-57326
CVSS 4.0: 6.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:N/SI:H/SA:N
Updated: 2026-11-02

GitHub AdvisoriesGHSA-4f3c-j3m4-8h7h 6.1

Nagios Core before 4.5.14 and Nagios XI before 2026R1.7 contain a cross-site request forgery...

Record: GHSA-4f3c-j3m4-8h7h
CVSS 4.0: 6.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:N/SI:H/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: 7.4 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:H/A:N
Weakness: CWE-352
Updated: 2026-11-02

NVD 6.1

Record: CVE-2026-48551
CVSS 4.0: 6.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:N/SI:H/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: 7.4 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:H/A:N
Weakness: CWE-352
Updated: 2026-11-02

OSV 6.1

Nagios Core / XI CSRF Protection Bypass via Double-Submit Cookie

Record: CVE-2026-48551
CVSS 4.0: 6.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:N/SI:H/SA:N
Weakness: CWE-352
Updated: 2026-11-02

OSVDEBIAN-CVE-2026-48551 6.1

Record: DEBIAN-CVE-2026-48551
CVSS 4.0: 6.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:N/SI:H/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-2026-48551 6.1

Record: UBUNTU-CVE-2026-48551
CVSS 4.0: 6.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:N/SI:H/SA:N
CVSS 3.1: 7.4 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:H/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-2026-48551 is a medium vulnerability (CVSS 6.1) 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 0.26%, the 18th percentile. Fixed in nagios4 4.4.6-4+deb12u2.