What is CVE-2026-8833?

CVE-2026-8833 is a publicly disclosed cybersecurity vulnerability with a HIGH severity rating and CVSS score of 8.5.

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CVE-2026-8833

HIGH8.5/ 10.0

Published: June 8, 2026 at 01:16 PM

Modified: June 17, 2026 at 11:04 AM

Source: security@checkmk.com

Vulnerability 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.

CVSS Metrics

Base Score

8.5

Severity

HIGH

Vector String

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