Medium severity · published Mar 13, 2026
CVE-2026-2859
Unauthenticated Host Enumeration via Observable Response Discrepancy on Deploy Agent Endpoint
4.3
CVSS
0.2%
EPSS
No
On KEV
Description
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 vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
Low
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 9% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CH
Checkmk · Checkmk GmbH
2.4.0 before 2.4.0p23; 2.3.0 before 2.3.0p43; 2.2.0 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-2859
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-2859
Vendor Advisory
https://checkmk.com/werk/18994
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