Check Point Advisories

Checkmk Cross-Site Scripting (CVE-2026-8833)

Vulnerability
Protection

Check Point Reference:	CPAI-2026-10493
Date Published:	30 Aug 2026
Severity:	Medium
Last Updated:	Sunday 30 August, 2026
Source:
Industry Reference:	CVE-2026-8833
Protection Provided by:	Security Gateway R81, R80, R77, R75
Who is Vulnerable?	Checkmk 2.5.0 and prior Checkmk 2.4.0 and prior Checkmk 2.3.0 and prior Checkmk 2.2.0
Vulnerability Description	A cross-site scripting vulnerability in Checkmk allows an authenticated user to bypass URL validation and inject malicious URLs such as javascript: URIs. This can result in cross-site scripting when another user interacts with the crafted link.

Protection Overview

This protection detects attempts to exploit this vulnerability.

In order for the protection to be activated, update your Security Gateway product to the latest IPS update. For information on how to update IPS, go to SBP-2006-05, click on Protection tab and select the version of your choice.

Security Gateway R81 / R80 / R77 / R75

In the IPS tab, click Protections and find the Checkmk Cross-Site Scripting (CVE-2026-8833) protection using the Search tool and Edit the protection's settings.
Install policy on all Security Gateways.

This protection's log will contain the following information:

Attack Name: Web Server Enforcement Violation.
Attack Information: Checkmk Cross-Site Scripting (CVE-2026-8833)