Home/CVE/Cross-Site Scripting (XSS) vulnerability in Checkmk's distributed monitoring allows a compromised remote site to inject
CVE

CVE-2025-39663

Cross-Site Scripting (XSS) vulnerability in Checkmk's distributed monitoring allows a compromised remote site to inject

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).

HIGH · CVSS 8.4 EPSS 0.00071
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  • Public exploit or PoC is available
  • CVSS base score ≥ 7.0
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-80Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)
▤

Affected Products & Versions

2
checkmk>= 2.0.0 and < 2.3.0
checkmkall versions
⚠

Public Exploits & PoCs

1
pocgithub.com · SBA-ADV-20250729-01_Checkmk_Cross_Site_Scriptinggithub.com
▣

Scoring & Timeline

8.4
HIGH · CVSS v3.1 · security@checkmk.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD30 Oct 2025 · 11:15 AM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:H
SSVC triage · cisa-vulnrichment
Exploitation
poc
Automatable
no
Technical impact
total
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
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References & Sources

2
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://checkmk.com/werk/17998Vendor Advisory
http://seclists.org/fulldisclosure/2025/Nov/0ExploitMailing ListThird Party Advisory
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