Checkmk up to 2.2.0/2.3.0p42/2.4.0p22 HTTP Response deploy_agent response discrepancy

CVSS Meta Temp Score
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CTI Interest Score
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4.7$0-$5k0.00

Summaryinfo

A vulnerability was found in Checkmk up to 2.2.0/2.3.0p42/2.4.0p22. It has been classified as problematic. This affects the function deploy_agent of the component HTTP Response Handler. The manipulation leads to response discrepancy. This vulnerability is documented as CVE-2026-2859. The attack can be initiated remotely. There is not any exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in Checkmk up to 2.2.0/2.3.0p42/2.4.0p22. This issue affects the function deploy_agent of the component HTTP Response Handler. The manipulation with an unknown input leads to a response discrepancy vulnerability. Using CWE to declare the problem leads to CWE-204. The product provides different responses to incoming requests in a way that reveals internal state information to an unauthorized actor outside of the intended control sphere. Impacted is confidentiality. The summary by CVE is:

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.

It is possible to read the advisory at checkmk.com. The identification of this vulnerability is CVE-2026-2859 since 02/20/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1592 according to MITRE ATT&CK.

The vulnerability scanner Nessus provides a plugin with the ID 302869 (Linux Distros Unpatched Vulnerability : CVE-2026-2859), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 2.3.0p43 or 2.4.0p23 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (302869). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 4.8
VulDB Meta Temp Score: 4.7

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 4.3
NVD Vector: 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Response discrepancy
CWE: CWE-204 / CWE-203 / CWE-200
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 302869
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-2859

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Checkmk 2.3.0p43/2.4.0p23

Timelineinfo

02/20/2026 CVE reserved
03/13/2026 +21 days Advisory disclosed
03/13/2026 +0 days VulDB entry created
03/20/2026 +7 days VulDB entry last update

Sourcesinfo

Advisory: checkmk.com
Status: Confirmed

CVE: CVE-2026-2859 (🔒)
GCVE (CVE): GCVE-0-2026-2859
GCVE (VulDB): GCVE-100-350831

Entryinfo

Created: 03/13/2026 11:29
Updated: 03/20/2026 06:20
Changes: 03/13/2026 11:29 (66), 03/19/2026 02:39 (2), 03/20/2026 06:20 (12)
Complete: 🔍
Cache ID: 216::103

Be aware that VulDB is the high quality source for vulnerability data.

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