CVE-2023-22288Network attack vector

Email content injection via unsanitized notification HTML

Published Mar 20, 2023 · Updated Feb 26, 2025

HTML injection in affected Checkmk releases allows remote authenticated users to insert malicious markup into email notifications. The Insert HTML section between body and table setting passes attacker-controlled markup into generated messages without the usual sanitization. The attacker needs permission to configure HTML notifications, and exploitation depends on a recipient viewing the crafted message; the reported impact is limited to information disclosure.

CVSS severity4.1
Medium
EPSS probability0.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

HTML injection in affected Checkmk releases allows remote authenticated users to insert malicious markup into email notifications. The Insert HTML section between body and table setting passes attacker-controlled markup into generated messages without the usual sanitization. The attacker needs permission to configure HTML notifications, and exploitation depends on a recipient viewing the crafted message; the reported impact is limited to information disclosure.

The record

CVE
CVE-2023-22288
Published
Mar 20, 2023
Updated
Feb 26, 2025
Vendor
Checkmk GmbH
Product
Checkmk
Classifications
CWE-138, CWE-79, CAPEC-242
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 20, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 26, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.6.0 <=1.6.0p30
  2. Affected versionversion=2.0.0 <=2.0.0p34
  3. Affected versionversion=2.1.0 <=2.1.0p23

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Checkmk GmbH · Checkmkversion=1.6.0 <=1.6.0p30; version=2.0.0 <=2.0.0p34; version=2.1.0 <=2.1.0p23

Published CVSS scores

5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
4.1Checkmk GmbHCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-138Improper Neutralization of Special Elements
CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CAPEC-242Code Injection

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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