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Status published
High
CVE-2025-39663
Cross Site Scripting through compromised remote site
Vulnerability Description
Cross-Site Scripting (XSS) vulnerability in Checkmk's distributed monitoring allows a compromised remote site to inject malicious HTML code into service outputs in the central site. Affecting Checkmk before 2.4.0p14, 2.3.0p39, 2.2.0 and 2.1.0 (eol).
Impact Analysis
Refer to official advisory for detailed impact metrics.
Remediation
Ensure systems are updated to the latest vendor-supplied patch levels.
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Credits & Attribution
The following person or organization is credited with identifying this vulnerability, as recorded in the NVD database:
- Lisa Gnedt (SBA Research)
References
More from Checkmk GmbH
View All →CVE-2025-65000
Exposure of SSH Private Keys in Remote Alert Handlers (Linux) Rule
Low
2.3
CVE-2025-64999
Cross-site scripting in HTML logs of Synthetic Monitoring test services
High
7.3
CVE-2025-64998
Session hijacking via exposed session signing secret in distributed Checkmk setups
High
7.3
CVE-2025-64997
Insufficient permission validation when showing agent information
Medium
6.3
CVE-2025-64996
Overly broad file permissions in the mk_inotify plugin allows reading and manipulating the plugin's output
Medium
4.8
Affected Vendor
Checkmk GmbH
View all reports →Affected Software
Checkmk
Vulnerable Versions:
2.4.0, 2.3.0, 2.2.0, 2.1.0
Timeline
Official Publish:
October 30th, 2025
Last Modified:
November 7th, 2025
Added to House:
July 22nd, 2026