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CVE-2026-121374VulnerabilityPublished

Checkmk <2.5.0p19, <2.4.0p40 · Argument Injection

Source GCVE Database

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Authoritative record:CVE-2026-121374· Critical 9.4

Not known to be exploited · CVSS 9.4 Critical : upgrade to 2.5.0p19 or 2.4.0p40 as a priority.

Data as of 11 Nov 2026, 13:32 UTC

CVSS 4.0 base score
9.4Critical
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (Checkmk)CVSS 4.09.4
Patch
Available – fixed in 2.5.0p19, 2.4.0p40
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 11 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 11 Nov 2026.

What to do

Upgrade Checkmk to 2.5.0p19 or 2.4.0p40.

Affected software

ProductAffectedFixed in
Checkmk GmbHCheckmkAffected
  • >=2.5.0 <2.5.0p19
  • >=2.4.0 <2.4.0p40
  • =2.3.0
Fixed in
  • 2.5.0p19
  • 2.4.0p40

AI-suggested

If you cannot patch yet, restrict rule editing permissions to trusted users only to mitigate risk.

Description

A critical argument injection vulnerability exists in the Kubernetes special agent component of Checkmk versions prior to 2.5.0p19, 2.4.0p40, and in the end-of-life 2.3.0 version. This flaw allows a user with permission to edit rules in at least one folder to write files to arbitrary locations writable by the site user by crafting node roles in the "Exclude nodes based on their role" rule option. Successful exploitation leads to code execution with the privileges of the site user.

References

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