Path traversal in host label synchronization allows code execution on the central site from a remote site
Affects Checkmk 2.4.0 before 2.4.0p40 and 2.5.0 before 2.5.0p19 in distributed monitoring setups with remote sites that may be untrusted. Fixed in 2.4.0p40 and 2.5.0p19.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 2.5.0p19, 2.4.0p40
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. Distributed monitoring setup where a remote site may be untrusted or compromised.
- Published
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 17/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
Checkmk is affected by a path traversal flaw in its discovered host label synchronization. An attacker who controls a remote site in a distributed monitoring setup can reach it over the network with low-privilege login and no user action, write arbitrary files on the central site, and execute code as the central site user.
Read the original description
Path traversal in the discovered host label synchronization in Checkmk <2.5.0p19, <2.4.0p40 and 2.3.0 (EOL) allows an attacker in control of a remote site in a distributed monitoring setup to write arbitrary files on the central site and thereby execute code as the central site user.
Who should check
Teams running Checkmk 2.5.0 before p19, 2.4.0 before p40, or 2.3.0 (EOL) in distributed setups with potentially untrusted remote sites.
Read the source excerpt
“Every setup with potentially untrusted remote sites is affected.”
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure8/25Specific setups only, reachable over the network
- Reach?/20Unknown. No tracked technology or package matched
- Severity9.4/10CVSS 9.4
- No patch0/5No signal
What would change the score
- Would score about 67 if added to CISA KEV
- Would score about 62 if CISA's SSVC rates exploitation active
- Would score about 24 if CISA's SSVC rates it automatable
What to do
Check whether your setup matches what the bug needs.
Distributed monitoring setup where a remote site may be untrusted or compromised.Upgrade to a fixed version: 2.5.0p19, 2.4.0p40.
Check your systems with an agent
Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.
Check whether my systems are affected by CVE-2026-118965 (Path traversal in host label synchronization allows code execution on the central site from a remote site), using the cve.now data below. Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only. What cve.now has for CVE-2026-118965 (entry last updated 2026-11-11): Affected: - Checkmk GmbH Checkmk: from 2.5.0, fixed in 2.5.0p19; from 2.4.0, fixed in 2.4.0p40 Fixed versions: 2.5.0p19, 2.4.0p40. Conditions (all must be true for the bug to be hit): - Distributed monitoring setup where a remote site may be untrusted or compromised. (source: https://checkmk.com/werk/22120) Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory. Attacker needs: network access, low-privilege login, no user action. CISA KEV: CVE-2026-118965 is not listed as of cve.now's last read. This KEV status is for CVE-2026-118965 only. If you also check another CVE, look up its own KEV status; never assume it from this one. How to check: - Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory. Verify against the linked advisories before concluding, and cite the date you read each one: - https://checkmk.com/werk/22120 Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing. Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action. Entry: https://cve.now/CVE-2026-118965 For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example get_vulnerability with id CVE-2026-118965.
Timeline
- CVE published
- First seen by cve.now
- Posted on X by cve.now
Affected versions
- Checkmk GmbH Checkmk
From 2.5.0 · fixed in 2.5.0p19; From 2.4.0 · fixed in 2.4.0p40
Evidence 3
CVE record · 2
Establishes: The identifier and description.
- Record
- Record
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-118965
Is CVE-2026-118965 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
A flaw in host label synchronization lets a malicious remote site write arbitrary files on the central site. Those files can lead to code execution on the central site.Source: checkmk.com
Which versions are affected by CVE-2026-118965?
Checkmk: from 2.5.0 before 2.5.0p19; from 2.4.0 before 2.4.0p40.Source: cve.now feed data
Am I affected, and how do I check?
Checkmk 2.4.0 before 2.4.0p40 and 2.5.0 before 2.5.0p19 are affected. The condition is a distributed monitoring setup where a remote site may be untrusted or compromised; the installed version can be compared against these ranges.Source: checkmk.com
How do I fix CVE-2026-118965?
Upgrade to Checkmk 2.4.0p40 or 2.5.0p19, matching the release line in use.Source: checkmk.com