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CVE-2026-8833— XSS in urls

Quick assessment

Affected
Checkmk GmbH Checkmk
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Checkmk是Checkmk公司的一个 IT 监控平台。 Checkmk 2.5.0p5之前版本、2.4.0p31之前版本、2.3.0p48之前版本和所有2.2.0版本存在跨站脚本漏洞，该漏洞源于URL验证函数中HTML编码字符的中和不当，允许经过身份验证的用户绕过URL验证并注入恶意URL如javascript: URI，导致其他用户与特制链接交互时发生跨站脚本攻击。

AI Predicted 6.1 Difficulty: Easy EPSS 0.14% · P3

Possible ATT&CK Techniques 1 AI

T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 4

VendorProduct Version RangeStatus
Checkmk GmbH Checkmk 2.5.0< 2.5.0p5 affected
2.4.0< 2.4.0p31 affected
2.3.0< 2.3.0p48 affected
2.2.0 affected
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I. Basic Information for CVE-2026-8833

Vulnerability Information
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Vulnerability Title
XSS in urls
Source: CVE Program / CVE List V5
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.
Source: CVE Program / CVE List V5
CVSS Information
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
Source: CVE Program / CVE List V5
Vulnerability Type
在Web页面生成时对输入的转义处理不恰当(跨站脚本)
Source: CVE Program / CVE List V5
Vulnerability Title
Checkmk 跨站脚本漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Checkmk是Checkmk公司的一个 IT 监控平台。 Checkmk 2.5.0p5之前版本、2.4.0p31之前版本、2.3.0p48之前版本和所有2.2.0版本存在跨站脚本漏洞，该漏洞源于URL验证函数中HTML编码字符的中和不当，允许经过身份验证的用户绕过URL验证并注入恶意URL如javascript: URI，导致其他用户与特制链接交互时发生跨站脚本攻击。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Checkmk GmbH Checkmk 2.5.0 ~ 2.5.0p5 -

II. Public POCs for CVE-2026-8833

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III. Intelligence Information for CVE-2026-8833

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Vendor Advisories for CVE-2026-8833 (1)

Same Patch Batch · Checkmk GmbH · 2026-06-08 · 5 CVEs total

CVE-2026-7186 Fix stored XSS in URL dashboard widget via dangerous URI schemes
CVE-2026-7765 User Messages widget leaked issuer messages on shared dashboards
CVE-2026-9549 Fix XSS in service discovery active check output
CVE-2026-8078 Fix stored XSS in global settings change log

IV. Related Vulnerabilities

Same product: Checkmk
Same vendor: Checkmk GmbH
Same weakness: CWE-79