Cyber Resilience

CVE-2026-33276

High

Published: 31 March 2026

Published
31 March 2026
Modified
02 April 2026
KEV Added
—
Patch
—
CVSS Score v4 8.6 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/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
EPSS Score 0.0014 4.0th percentile
Risk Priority 55 floored blend · peak EPSS

Summary

CVE-2026-33276 is a high-severity Cross-site Scripting (CWE-79) vulnerability in Checkmk Checkmk. Its CVSS base score is 8.6 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique JavaScript (T1059.007); ranked at the 4.0th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

OWASP Top 10 for Web (2025)

A05:2025 Injection

EU & UK References

Vulnerability details

Stored cross-site scripting (XSS) in Checkmk 2.5.0 (beta) before 2.5.0b2 allows authenticated users with permission to create hosts or services to execute arbitrary JavaScript in the browsers of other users performing searches in the Unified Search feature.

CWE(s)
CWE-79

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1059.007 JavaScript Execution
Adversaries may abuse various implementations of JavaScript for execution.
attack.mitre.org →
T1185 Browser Session Hijacking Collection
Adversaries may take advantage of security vulnerabilities and inherent functionality in browser software to change content, modify user-behaviors, and intercept information as part of various browser session hijacking techniques.
attack.mitre.org →
Why these techniques?

Stored XSS enables arbitrary JavaScript execution in victim browsers (T1059.007) and facilitates browser session hijacking (T1185).

Confidence: MEDIUM · MITRE ATT&CK Enterprise v19.0

Affected Assets

checkmk
checkmk
2.5.0

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

CA-8 Penetration Testing
addresses: CWE-79

Penetration testing submits XSS payloads to web applications, detecting cross-site scripting flaws for subsequent remediation.

SI-10 Information Input Validation
addresses: CWE-79

Validates web inputs to reject script-related content that could produce XSS.

SI-15 Information Output Filtering
addresses: CWE-79

Output validation against expected content can reject or sanitize script content in generated web pages, reducing XSS exploitability.

References