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CVE.org (no NVD analysis yet)· CNA Checkmk

CVE-2026-120495: Arbitrary file write and code execution via crafted Synthetic Monitoring agent data

CriticalCVSS 9.4 · v4.0—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 37/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.46% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Checkmk GmbH Checkmk 2.4.0p40, 2.5.0p19.

Low priority for now. Upgrade to Checkmk GmbH Checkmk 2.4.0p40, 2.5.0p19 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

Path traversal in the Synthetic Monitoring "Robotmk" test service of Checkmk <2.5.0p19, <2.4.0p40, and 2.3.0 (EOL) allows an attacker who controls the agent output of a monitored host's check output for a host to inject a crafted robot output to define the contents and location for the generated HTML log, leading to code execution as the site user.

Published
Nov 11, 2026
Updated
Nov 11, 2026
EPSS
0.4% · 40th percentile

Report tools

JSON

Action score

37

Monitor

Low priority for now.

CVSS
37 / 40 · 9.4 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.4%

CNA vs NVD score

NVD
—
CNA · Checkmk
9.4
NVD has not scored this yet; the score shown is the CNA’s.

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-120495

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Checkmk). Independent of NVD's CPE analysis and usually ahead of it.

  • Checkmk GmbH Checkmk

    • 2.3.0affected
    • 2.5.0 and later · before 2.5.0p19affected · semver
    • 2.4.0 and later · before 2.4.0p40affected · semver

Same product

checkmk gmbh: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-121374Arbitrary file write and code execution via excluded node roles in Kubernetes special agent
    37Monitor
  • CVE-2026-118965Path traversal in host label synchronization allows code execution on the central site from a remote site
    37Monitor
  • CVE-2026-14452Open redirect and XSS via reset_url parameter
    34Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2026-103674Nov 6, 2026 · NetApp ONTAP special agent exposes password in process list
    8Monitor
  • ← EarlierCVE-2026-103682Nov 6, 2026 · Jolokia special agent exposes password in process list
    8Monitor
  • ← EarlierCVE-2026-111573Nov 6, 2026 · Privilege escalation via unprotected Windows agent data folder
    25Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Checkmk GmbH Checkmk2.4.0p40Vendor (CNA)
Checkmk GmbH Checkmk2.5.0p19Vendor (CNA)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. Fix recordedsame day
  3. TodayNov 13, 2026+2 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

  • CVE-2026-1557682 days apartAgent receiver accepts mTLS requests without a client certificate
    27Monitor

Not on record for this CVE: patch commit or PR link · researcher credit · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability
Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
X

Weakness class (CWE)

CWE-23 · Relative Path Traversal

CVSS vector

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records