High 7.3Published Feb 26, 2026

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

Updated under an hour ago (Oct 28, 2026, 10:40 AM ET)

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It affects Checkmk GmbH Checkmk. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for Checkmk GmbH Checkmk

Exploited in the last 30 days

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.

CVSS: 7.3 HIGH (v4.0, CNA)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
Weakness (CWE): CWE-79
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Checkmk
NVD analysis: Modified
Record last updated: Apr 14, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Checkmk GmbH Checkmk checkmk:checkmk (from the name)	from 2.4.0 before 2.4.0p22; from 2.3.0 before 2.3.0p43	CNA record
checkmk checkmk checkmk:checkmk	2.3.0; 2.3.0; 2.3.0; 2.3.0; 2.3.0; 2.3.0; 2.3.0; 2.3.0; and 69 more ranges	NVD

References

References

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

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.