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.

Attack Vector Network

Attack Complexity Low

Privileges Required Low

Attack Requirements None

User Interaction Active

Vulnerable System Confidentiality Impact High

Vulnerable System Integrity Impact High

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact Low

Subsequent System Availability Impact None

No CVSS v3.1

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Exploitation none

Automatable no

Technical Impact total

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
Checkmk GmbH Checkmk unaffected
Version Status Constraints
2.5.0 affected < 2.5.0p5
2.4.0 affected < 2.4.0p31
2.3.0 affected < 2.3.0p48
2.2.0 affected —

No data.

No data.

No data.

Project Subscriptions

Vendors Products
Checkmk Subscribe
Checkmk Subscribe
Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://checkmk.com/werk/20002 cve-icon cve-icon
History

Mon, 08 Jun 2026 13:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Mon, 08 Jun 2026 13:00:00 +0000

Type Values Removed Values Added
Description 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.
Title XSS in urls
First Time appeared Checkmk
Checkmk checkmk
Weaknesses CWE-79
CPEs cpe:2.3:a:checkmk:checkmk:*:*:*:*:*:*:*:*
cpe:2.3:a:checkmk:checkmk:2.2.0:*:*:*:*:*:*:*
Vendors & Products Checkmk
Checkmk checkmk
References
Metrics cvssV4_0

{'score': 8.5, 'vector': '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'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Checkmk

Published:

Updated: 2026-06-08T13:02:45.679Z

Reserved: 2026-05-18T14:06:43.958Z

Link: CVE-2026-8833

cve-icon Vulnrichment

Updated: 2026-06-08T13:02:42.423Z

cve-icon NVD

Status : Received

Published: 2026-06-08T13:16:33.900

Modified: 2026-06-08T13:16:33.900

Link: CVE-2026-8833

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses