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CheckmkApplication

CVE-2023-22288

MEDIUM · 5.4 CVSS v3.1 Published 2023-03-20
Fix available
A fix is available. Upgrade to 2.0.0 or later.
See remediation →
58/100
Remediation priority · Elevated
Remotely reachable

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
HTML Email Injection in Tribe29 Checkmk <=2.1.0p23; <=2.0.0p34, and all versions of Checkmk 1.6.0 allows an authenticated attacker to inject malicious HTML into Emails

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

HTML Email Injection vulnerability in Tribe29 Checkmk allows authenticated attackers to inject malicious HTML into generated emails due to insufficient input validation and output encoding of email content.

MitigationImplement proper HTML entity encoding/escaping for all user-controlled content in email templates, combined with input validation to reject or sanitize HTML tags in email fields.

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:= 2.0.0= 2.1.0
CheckmkApplication
Affected:>= 1.6.0, < 2.0.0

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
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

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

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 Checkmk installation and version
    Run command: 'cmk --version' or check /opt/checkmk/version', or if using OMD: 'omd version <sitename>'
    Affected if Installed version matches 1.6.0 through 1.6.x, or is exactly 2.0.0 or 2.1.0
  2. Verify email notifications are enabled
    Check if any notification rule or email receiver is configured in Checkmk: navigate to Setup > Notifications or check for notification configuration files in the etc/ directory of the Checkmk site
    Affected if Email notifications are configured and active in the Checkmk environment
  3. Check for custom notification parameters
    Review notification configuration for any user-controlled fields that populate email content, such as custom message templates, sender/recipient addresses, or notification plugin parameters
    Affected if Custom notification parameters accept user input that could be injected into email body or headers
  4. Confirm authentication to Checkmk
    Verify that user accounts exist and can access notification/alert configuration areas in Checkmk web interface or API
    Affected if Attacker can authenticate to Checkmk with privileges to create or modify notification rules

User is affected if Checkmk version is 1.6.0-1.6.x, 2.0.0, or 2.1.0 AND email notifications are enabled AND authenticated users can modify notification settings with custom parameters.

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
Upgrade available Upgrade to 2.0.0 or later
Fixed in 2.0.0
Interim mitigation

Implement proper HTML entity encoding/escaping for all user-controlled content in email templates, combined with input validation to reject or sanitize HTML tags in email fields.

Recommended fix High confidence

Checkmk 2.1.0p24 or later (or 2.0.0p35 or later if staying on 2.0.x branch)

  1. 1. Identify the currently installed Checkmk version using 'cmk --version' or the web interface Help > About page
  2. 2. For Checkmk 2.1.0.x: Upgrade to version 2.1.0p24 or later
  3. 3. For Checkmk 2.0.0.x: Upgrade to version 2.0.0p35 or later
  4. 4. For Checkmk 1.6.0.x: Upgrade to a supported version (2.0.0p35 or later, or 2.1.0p24 or later)
  5. 5. Download the updated Checkmk raw or enterprise edition from the official Checkmk download site
  6. 6. Follow the standard Checkmk upgrade documentation for your deployment type (standalone or distributed)
  7. 7. After upgrade, verify the fix by testing email notification functionality
Caveat Checkmk upgrades may require migration steps; review release notes for behavioral changes between versions

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

Fix this in Checkmk Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
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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-2023-22288 in production — separate from our analysis above.

No notes yet

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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