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CVE-2026-2859

Unauthenticated Host Enumeration via Observable Response Discrepancy on Deploy Agent Endpoint

Medium6.3EPSS 0.20%
Published
Updated
Reserved
Assigned by
Checkmk

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.

Scores

CVSS scores of CVE-2026-2859, by who scored it
Scored byCVSSScoreVector
CheckmkCNA (assigner)4.0Medium6.3CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
NVDNVD · Analyzed4.0Medium6.3CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/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
EPSS (exploitation in 30 days)
0.20% · top 90% of all CVEs (6 Nov 2026)
CISA SSVC
Exploitation: none · Automatable: yes · Technical impact: partial
Loading the EPSS history…

The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.3.

Weakness

Affected products

  • Checkmk GmbH · Checkmk

    • affected 2.4.0 – < 2.4.0p23
    • affected 2.3.0 – < 2.3.0p43
    • affected 2.2.0

References (1)

Sources

The same CVE in the primary databases and aggregators, to check against.

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Record last updated .