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Vulnerability record · CVE-2025-39663 · published 30 October 2025

CVE-2025-39663: Checkmk cross-site scripting vulnerability

Checkmk · Checkmk

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).

8.5 CVSS 4.0 High EPSS 0.56% · top 55.4% CWE-80 · CWE-80CWE-79 · Cross-site scripting
8.5CVSS 4.0 base score
0.56%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References, 3 tagged exploit
17 Jun 2026Last modified by NVD

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).

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://checkmk.com/werk/17998 Vendor Advisory
https://github.com/sbaresearch/advisories/tree/82fd27e4570433464c30b35150b197db9a850f4e/2025/SBA-ADV-20250729-01_Checkmk ExploitThird Party Advisory
http://seclists.org/fulldisclosure/2025/Nov/0 ExploitMailing ListThird Party Advisory
https://github.com/sbaresearch/advisories/tree/82fd27e4570433464c30b35150b197db9a850f4e/2025/SBA-ADV-20250729-01_Checkmk ExploitThird Party Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2024-28825Checkmk improper restriction of authentication attempts vulnerabilityImproper restriction of excessive authentication attempts on some authentication methods in Checkmk before 2.3.0b5 (beta), 2.2.0p26, 2.1.0p43, and in…EPSS 0.52%9.8CVE-2022-48317Checkmk insufficient session expiration vulnerabilityExpired sessions were not securely terminated in the RestAPI for Tribe29's Checkmk <= 2.1.0p10 and Checkmk <= 2.0.0p28 allowing an attacker to use ex…EPSS 0.46%9.3CVE-2025-39666Checkmk untrusted search path vulnerabilityLocal privilege escalation in Checkmk 2.2.0 (EOL), Checkmk 2.3.0 before 2.3.0p46, Checkmk 2.4.0 before 2.4.0p25, and Checkmk 2.5.0 (beta) before 2.5.…EPSS 0.12%9.2CVE-2024-8606Checkmk incorrect authorization vulnerabilityBypass of two factor authentication in RestAPI in Checkmk < 2.3.0p16 and < 2.2.0p34 allows authenticated users to bypass two factor authenticationEPSS 0.46%8.8CVE-2025-32919Checkmk uncontrolled search path element vulnerabilityUse of an insecure temporary directory in the Windows License plugin for the Checkmk Windows Agent allows Privilege Escalation. This issue affects Ch…EPSS 0.27%8.8CVE-2024-28828Checkmk cross-site request forgery vulnerabilityCross-Site request forgery in Checkmk < 2.3.0p8, < 2.2.0p29, < 2.1.0p45, and <= 2.0.0p39 (EOL) could lead to 1-click compromize of the site.EPSS 0.25%8.8CVE-2023-6156Checkmk vulnerabilityImproper neutralization of livestatus command delimiters in the availability timeline in Checkmk <= 2.0.0p39, < 2.1.0p37, and < 2.2.0p15 allows arbit…EPSS 0.86%8.8CVE-2023-6157Checkmk vulnerabilityImproper neutralization of livestatus command delimiters in ajax_search in Checkmk <= 2.0.0p39, < 2.1.0p37, and < 2.2.0p15 allows arbitrary livestatu…EPSS 0.89%

Source: NIST National Vulnerability Database (record CVE-2025-39663), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.