Vulnerability · Published Aug 12, 2026 · Assigned by VulnCheck
CVE-2026-48551Nagios Core / XI CSRF Protection Bypass via Double-Submit Cookie
High 7.4
In plain English
A high-severity cross-site request forgery in Nagios Core from Nagios Enterprises, LLC.. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 18% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | nagios4 | 4.4.6-4+deb12u2 | DEBIAN-CVE-2026-48551 |
| Debian:13 | nagios4 | 4.4.6-4.1+deb13u2 | DEBIAN-CVE-2026-48551 |
| Debian:14 | nagios4 | 4.5.14+ds-1 | DEBIAN-CVE-2026-48551 |
| Ubuntu:22.04:LTS | nagios4 | no fix listed | UBUNTU-CVE-2026-48551 |
| Ubuntu:24.04:LTS | nagios4 | no fix listed | UBUNTU-CVE-2026-48551 |
| Ubuntu:26.04:LTS | nagios4 | no fix listed | UBUNTU-CVE-2026-48551 |
| Ubuntu:26.10 | nagios4 | no fix listed | UBUNTU-CVE-2026-48551 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Nagios Enterprises, LLC. | Nagios Core | 0 – before 4.5.14 |
| Nagios Enterprises, LLC. | Nagios XI | 0 – before 2026R1.7 |
Weakness: CWE-352 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:H/A:N
References
- Security Disclosures vendor-advisory, patch
- Changelog release-notes
- https://www.vulncheck.com/advisories/nagios-core-xi-csrf-protection-bypass-via-double-submit-cookie third-party-advisory