CVE-2026-24095 Overview
CVE-2026-24095 is an improper permission enforcement vulnerability affecting Checkmk, an open-source IT monitoring platform. This authorization bypass flaw allows users with the "Use WATO" permission to access the "Analyze configuration" page by directly navigating to its URL, effectively bypassing the intended "Access analyze configuration" permission check. When combined with the "Make changes, perform actions" permission, attackers can perform unauthorized administrative actions including disabling checks and acknowledging monitoring results.
Critical Impact
Authenticated users can bypass permission controls to access sensitive configuration analysis functionality and perform unauthorized administrative actions on the monitoring infrastructure.
Affected Products
- Checkmk version 2.4.0 before 2.4.0p21
- Checkmk version 2.3.0 before 2.3.0p43
- Checkmk version 2.2.0 (End of Life)
Discovery Timeline
- 2026-02-09 - CVE CVE-2026-24095 published to NVD
- 2026-02-09 - Last updated in NVD database
Technical Details for CVE-2026-24095
Vulnerability Analysis
This vulnerability stems from Missing Authorization (CWE-862) in Checkmk's web interface permission handling. The authorization logic fails to properly validate user permissions when the "Analyze configuration" page is accessed directly via URL navigation. The vulnerability allows users who possess the "Use WATO" (Web Administration Tool) permission to circumvent the more restrictive "Access analyze configuration" permission check that should gate access to this functionality.
The impact is particularly significant when the exploiting user also holds the "Make changes, perform actions" permission, as this combination enables them to execute administrative operations that should require the "Access analyze configuration" privilege. Actions such as disabling monitoring checks or acknowledging results can undermine the integrity of the entire monitoring infrastructure.
Root Cause
The root cause is a missing authorization check in the URL routing logic for the "Analyze configuration" page. While the web interface properly restricts access through normal navigation paths by checking for the "Access analyze configuration" permission, direct URL access bypasses this check, relying only on the broader "Use WATO" permission validation.
Attack Vector
The attack vector is network-based and requires low-privileged authenticated access. An attacker must first authenticate to the Checkmk instance with a user account that has at least the "Use WATO" permission. By directly navigating to the URL for the "Analyze configuration" page, the attacker bypasses the intended permission controls.
The exploitation flow is as follows:
- Attacker authenticates with credentials that have "Use WATO" permission but lack "Access analyze configuration" permission
- Attacker constructs or discovers the direct URL to the "Analyze configuration" page
- Browser navigates directly to the URL, bypassing the UI-level access control
- If the attacker also has "Make changes, perform actions" permission, they can disable checks or acknowledge results without proper authorization
Detection Methods for CVE-2026-24095
Indicators of Compromise
- Unexpected access to the "Analyze configuration" page by users without the "Access analyze configuration" permission
- Configuration changes or check acknowledgments performed by users who should not have access to configuration analysis functionality
- Audit log entries showing direct URL navigation to administrative pages by lower-privileged users
Detection Strategies
- Review Checkmk audit logs for access patterns to the "Analyze configuration" page, cross-referencing against user permission assignments
- Monitor for users accessing administrative URLs directly without navigating through the expected UI workflow
- Implement alerting on configuration changes or acknowledgments from users without appropriate permissions
Monitoring Recommendations
- Enable comprehensive audit logging in Checkmk to capture all access to administrative pages
- Establish baseline access patterns for the "Analyze configuration" page to identify anomalous direct URL access
- Configure alerts for any modifications to monitoring checks or acknowledgment of results by non-administrative users
How to Mitigate CVE-2026-24095
Immediate Actions Required
- Upgrade Checkmk to version 2.4.0p21 or later for the 2.4.x branch
- Upgrade Checkmk to version 2.3.0p43 or later for the 2.3.x branch
- Migrate away from Checkmk version 2.2.0 as it has reached End of Life
- Review user permissions and remove "Make changes, perform actions" from any users who do not require it pending upgrade
Patch Information
Checkmk has released patched versions that properly enforce the "Access analyze configuration" permission check for direct URL access. The fix is available in versions 2.4.0p21 and 2.3.0p43. Details about the fix can be found in the Checkmk Change Log Entry.
Workarounds
- Review and restrict the "Use WATO" permission to only those users who absolutely require it
- Remove the "Make changes, perform actions" permission from users who do not need to perform configuration modifications
- Implement network-level access controls to restrict access to the Checkmk web interface from trusted networks only
- Monitor audit logs closely for any unauthorized access attempts until patching can be completed
# Example: Review Checkmk version and plan upgrade
omd version
# Check current site version
omd sites
# Plan upgrade to patched version 2.4.0p21 or 2.3.0p43
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
