# CVE-2026-33276: Checkmk stored XSS in Unified Search via host or service names

Source: https://junglewise.ai/threats/cve-2026-33276-checkmk-stored-xss-in-unified-search-via-host-or-service-names  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-03-31. Updated: 2026-07-24  
License: CC BY 4.0 with a link back

CVE-2026-33276 · Severity: medium · CVSS 5.4 · Published 2026-03-31

Checkmk is an IT infrastructure monitoring platform. A security flaw in its search feature allows an authorized user to create specially named monitoring targets (hosts or services) that contain malicious code. If another administrator or user searches for these items, the malicious code will run in their browser, potentially allowing the attacker to steal session information or perform actions on their behalf.

Technologies: [Checkmk](https://junglewise.ai/threats/technologies/checkmk). Vendors: [Checkmk](https://junglewise.ai/threats/vendors/checkmk).

## Quick answers

**Is CVE-2026-33276 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-33276 being exploited in the wild.

**How severe is CVE-2026-33276?** Medium severity, with a CVSS score of 5.4, published 31 March 2026.

**Which products and versions are affected?** Checkmk GmbH Checkmk 2.5.0 (beta) before 2.5.0b2.

**Is there a fix for CVE-2026-33276?** A patch was published on 2026-03-23: Fix released in version 2.5.0b2 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-33276 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-33276?** Check whether you run Checkmk. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A stored cross-site scripting (XSS) vulnerability exists in the Unified Search feature of Checkmk. The root cause is the failure to properly sanitize host and service names before rendering them in search results. An authenticated attacker with permissions to create or modify hosts/services can inject malicious JavaScript into these object names. When another user performs a search that returns these objects, the payload executes in their browser context. This vulnerability was addressed in version 2.5.0b2.

## Affected products

- Checkmk GmbH Checkmk 2.5.0 (beta) before 2.5.0b2

## Timeline

- 2026-03-23: patched: Fix released in version 2.5.0b2
- 2026-03-31: disclosed: Initial advisory publication

## References

- [https://checkmk.com/werk/19525](https://checkmk.com/werk/19525)

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