Vulnerability · Published Oct 30, 2025 · Assigned by Checkmk
CVE-2025-39663Cross Site Scripting through compromised remote site
High 8.5
In plain English
A high-severity security flaw in Checkmk from Checkmk GmbH. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 49% of all known vulnerabilities).
Severity (CVSS 4.0)8.5High
Exploit odds (30 days)0.6%top 51.0% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known
Official 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).
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Checkmk GmbH | Checkmk | 2.4.0 – before 2.4.0p142.3.0 – before 2.3.0p392.2.02.1.0 |
Weakness: CWE-80 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N