EUVD-2026-35052
GHSA-c2x3-wx4h-g26v
Severity by source
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:N/VI:L/VA:N/SC:N/SI:L/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:X/V:X/RE:X/U:X
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:N/VI:L/VA:N/SC:N/SI:L/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:X/V:X/RE:X/U:X
Lifecycle Timeline
3DescriptionCVE.org
Stored cross-site scripting in the global settings change log in Checkmk <2.5.0p5, <2.4.0p31, <2.3.0p48, and all 2.2.0 versions allows an administrator who can change global settings to store malicious HTML or JavaScript in changelog messages that executes in other users' browsers when they view the Activate Changes page or Audit log.
AnalysisAI
Stored cross-site scripting in Checkmk's global settings change log enables a high-privileged administrator to persist malicious HTML or JavaScript within changelog messages, which then executes silently in the browsers of other authenticated users who view the Activate Changes page or Audit log. Affected versions span all 2.2.0 releases and builds prior to 2.5.0p5, 2.4.0p31, and 2.3.0p48. No active exploitation is confirmed (not listed in CISA KEV), and no public exploit code has been identified at time of analysis; however, the insider-threat angle - an already-privileged admin targeting peer users - is the realistic concern here.
Technical ContextAI
Checkmk (CPE: cpe:2.3:a:checkmk_gmbh:checkmk:*:*:*:*:*:*:*:*) is a widely deployed IT infrastructure and application monitoring platform. The vulnerability resides in the global settings change log subsystem, where changelog messages written by administrators are stored server-side and later rendered in the Activate Changes page and Audit log views without sufficient output encoding. CWE-79 (Improper Neutralization of Input During Web Page Generation - 'Cross-site Scripting') in its stored variant means the payload persists in the application's backend and is replayed to every user who loads the affected views, as opposed to reflected XSS which requires per-request delivery. The root cause is a failure to apply context-aware HTML encoding to administrator-supplied free-text fields before they are written into page output.
RemediationAI
The primary remediation is to upgrade to a patched release: Checkmk 2.5.0p5, 2.4.0p31, or 2.3.0p48, depending on the deployed branch, as documented in the vendor advisory at https://checkmk.com/werk/17992. Users on the 2.2.0 branch have no patched version available for that release line and should upgrade to a supported and patched branch (2.3.x, 2.4.x, or 2.5.x). As a compensating control for environments where immediate upgrade is not possible, strictly audit and limit which accounts hold the 'change global settings' permission, reducing it to the smallest set of fully trusted administrators - this directly limits who can inject payloads. Additionally, advise users with access to the Activate Changes and Audit log pages to treat unexpected or unfamiliar changelog entries with caution, though this is not a reliable technical control. Note that restricting global settings permissions may impact operational workflows if multiple administrators currently share that role.
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Same weakness CWE-79 – Cross-site Scripting (XSS)
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External POC / Exploit Code
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