CVE-2026-2859mediumCWE-204

CVE-2026-2859: medium-severity vulnerability in Checkmk

Unauthenticated Host Enumeration via Observable Response Discrepancy on Deploy Agent Endpoint

Published

Follow this CVE+ Monitor Checkmk

E-mail alert when it lands in KEV, gets a public PoC or its score goes up.

13Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 6.3epss 0.2%
Improper permission enforcement in Checkmk versions 2.4.0 before 2.4.0p23, 2.3.0 before 2.3.0p43, and 2.2.0 (EOL) allows unauthenticated users to enumerate existing hosts by observing different HTTP response codes in deploy_agent endpoint, which could lead to information disclosure.
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
Affected products
Checkmk GmbH · Checkmk
Related CVEs — Checkmk

In the same product, most dangerous first.

CVE-2023-31209HIGHCommand injection via active checks and REST APIEPSS 1.1%CVE-2023-31208HIGHLivestatus command injection in RestAPIEPSS 1.0%CVE-2023-6157HIGHLivestatus injection in ajax_searchEPSS 0.9%CVE-2024-38865MEDIUMLivestatus command injection in RestAPIEPSS 0.9%CVE-2023-6156HIGHLivestatus injection in availability timelineEPSS 0.9%CVE-2025-1712HIGHArbitrary file write with vcrtraceEPSS 0.8%