What’s Vulnerable › Vulnerabilities

CVE-2026-48551: Nagios Core / XI CSRF Protection Bypass via Double-Submit Cookie

• Severity: high (CVSS 7.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-12 · updated 2026-09-08
• Weakness: CWE-352

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 products

• Nagios Enterprises, LLC. Nagios Core: before 4.5.14 — fixed in 4.5.14
• Nagios Enterprises, LLC. Nagios XI: before 2026R1.7 — fixed in 2026R1.7

How to fix

Upgrade to a fixed version: Nagios Enterprises, LLC. Nagios Core 4.5.14; Nagios Enterprises, LLC. Nagios XI 2026R1.7. Check the vendor advisory for mitigations.

References

• https://github.com/NagiosEnterprises/nagioscore/blob/master/Changelog
• https://www.nagios.com/security-disclosures/nagios-core/
• https://www.vulncheck.com/advisories/nagios-core-xi-csrf-protection-bypass-via-double-submit-cookie

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