CVE-2025-64999

Cross-site scripting in HTML logs of Synthetic Monitoring test services

State: Published
Severity: 7.3 High
Published: Feb 26, 2026
Updated: Apr 14, 2026
Reserved: Nov 12, 2025

Description

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.

Scores

CVSS	Score	Vector	Source
4.0	7.3 High	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	Checkmk

Weaknesses

CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Affected Products

Product	Versions
CheckmkCheckmk GmbH	2.4.0 to before 2.4.0p22Affected 2.3.0 to before 2.3.0p43Affected

References

https://checkmk.com/werk/19238vendor-advisory
https://github.com/sbaresearch/advisories/tree/e72ce9bb6b9ffffc1fc35e4d8152ad153293c851/2025/SBA-ADV-20251118-01_Checkmk_Cross_Site_Scriptingthird-party-advisory

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