CVE-2025-64999 HIGH

CVE-2025-64999: Cross-site scripting in HTML logs of Synthetic Monitoring test services

Vendor Checkmk Gmbh
Product Checkmk
Weakness CWE-79 · XSS
Published February 26, 2026
Last update April 14, 2026
View on NVD All CVEs

CVSS base score

7.3/10
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction —
Confidentiality —
Integrity —

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:H/VI:H/VA:H/SC:N/SI:L/SA:N

What the vulnerability does

01Description

Improper neutralization of input in Checkmk versions 2.4.0 before 2.4.0p22, and 2.3.0 before 2.3.0p43 allows an attacker that can manipulate a host's check output to inject malicious JavaScript into the Synthetic Monitoring HTML logs, which can then be accessed via a crafted phishing link.

Key dates

02Disclosure timeline

February 26, 2026 CVE published
April 14, 2026 Record updated