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CheckmkApplication

CVE-2026-33456

HIGH · 7.6 CVSS v3.1 Published 2026-04-10
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
82/100
Remediation priority · High
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Livestatus injection in the notification test mode in Checkmk <2.5.0b4 and <2.4.0p26 allows an authenticated user with access to the notification test page to inject arbitrary Livestatus commands via a crafted service description.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Livestatus injection vulnerability in Checkmk's notification test mode allows authenticated users with access to the notification test page to inject arbitrary Livestatus commands by providing a crafted service description. The vulnerability stems from insufficient input validation in the notification test functionality.

MitigationUpgrade to Checkmk version 2.5.0b4 or 2.4.0p26 or later to apply the patch that adds proper input sanitization for service descriptions in the notification test mode.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
CheckmkApplication
Affected:= 2.4.0= 2.5.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Checkmk version
    Run 'omd version' command or check the Checkmk web interface footer for the version number
    Affected if The installed version is exactly 2.4.0 or exactly 2.5.0 (not patched to p26 or b4 and later)
  2. Verify user has access to notification test page
    Log into Checkmk as an authenticated user and navigate to the notification test functionality (typically found in Setup > Notifications or via a dedicated test notification endpoint)
    Affected if The authenticated user can access and use the notification test mode interface
  3. Confirm Livestatus module is enabled
    Check if Livestatus is running via 'cmk -L' or by querying the Livestatus socket at /var/run/checkmk/live or /opt/omd/sites/[site]/var/run/live.sock
    Affected if Livestatus is enabled and accessible (required for the injection to execute commands)
  4. Check user role permissions for notification configuration
    Review user permissions in Setup > Users > [user] > Roles to determine if the user has rights to access notification test functionality
    Affected if User role permits access to notification test or notification configuration features

The environment is affected if running exactly Checkmk 2.4.0 or 2.5.0 AND an authenticated user with notification test access can submit a crafted service description to the notification test interface while Livestatus is enabled.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to Checkmk version 2.5.0b4 or 2.4.0p26 or later to apply the patch that adds proper input sanitization for service descriptions in the notification test mode.

Recommended fix High confidence

Checkmk 2.4.0p26 (or later stable 2.4.x patch) / Checkmk 2.5.0b4 or later 2.5.x release

  1. 1. Identify your current Checkmk installation version (2.4.0 or 2.5.0)
  2. 2. For installations on 2.4.x branch: Upgrade to Checkmk version 2.4.0p26 or later stable patch release
  3. 3. For installations on 2.5.x branch: Upgrade to Checkmk version 2.5.0b4 or later (consider waiting for stable 2.5.0 release if currently on beta)
  4. 4. After upgrade, verify the Livestatus injection vulnerability is resolved by reviewing release notes for the target version
  5. 5. Test the notification test mode functionality to confirm normal operation after patching
Caveat Review release notes for any configuration or feature changes between your current version and target version before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Checkmk Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA2.0 h
9.0 hours of engineering $1,600
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-33456 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data