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Checkmk CVE-2026-8833

| EUVDEUVD-2026-35053 HIGH
Cross-site Scripting (XSS) (CWE-79)
2026-06-08 Checkmk GHSA-hc7p-6r8x-vr4q
8.5
CVSS 4.0 · NVD
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Severity by source

NVD PRIMARY
8.5 HIGH
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:H/VI:H/VA:H/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:L/UI:A/VC:H/VI:H/VA:H/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
Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
A
Scope
X

Lifecycle Timeline

3
Patch available
Jun 08, 2026 - 14:01 EUVD
Analysis Generated
Jun 08, 2026 - 13:47 vuln.today
CVSS changed
Jun 08, 2026 - 13:22 NVD
8.5 (HIGH)

DescriptionCVE.org

Improper neutralization of HTML-encoded characters in the URL validation function in Checkmk <2.5.0p5, <2.4.0p31, <2.3.0p48, and all 2.2.0 versions allows an authenticated user to bypass URL validation and inject malicious URLs such as javascript: URIs, resulting in cross-site scripting when another user interacts with the crafted link.

AnalysisAI

Stored/reflected cross-site scripting in Checkmk monitoring platform versions prior to 2.5.0p5, 2.4.0p31, 2.3.0p48, and all 2.2.0 releases allows authenticated users to bypass URL validation by leveraging HTML-encoded characters, enabling injection of javascript: URIs that execute in another user's browser session. The CVSS 4.0 score of 8.5 reflects the high impact on confidentiality, integrity, and availability when a victim interacts with a crafted link, though no public exploit identified at time of analysis and the issue requires both low-privilege authentication and user interaction.

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CVE-2026-8833 vulnerability details – vuln.today

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