Checkmk up to 2.2.0/2.3.0p47/2.4.0p30/2.5.0p4 Service Discovery cross site scripting

CVSS Meta Temp Score
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CTI Interest Score
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2.3$0-$5k0.00

Summaryinfo

A vulnerability marked as problematic has been reported in Checkmk up to 2.2.0/2.3.0p47/2.4.0p30/2.5.0p4. This impacts an unknown function of the component Service Discovery. The manipulation leads to cross site scripting. This vulnerability is documented as CVE-2026-9549. The attack can be initiated remotely. There is not any exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in Checkmk up to 2.2.0/2.3.0p47/2.4.0p30/2.5.0p4. This issue affects an unknown code of the component Service Discovery. The manipulation with an unknown input leads to a cross site scripting vulnerability. Using CWE to declare the problem leads to CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Impacted is integrity. The summary by CVE is:

Stored cross-site scripting in the service discovery active check output in Checkmk <2.5.0p5, <2.4.0p31, <2.3.0p48, and all 2.2.0 versions allows an administrator who can configure active or custom checks to inject malicious HTML or JavaScript into check output that executes in the browser of an admin or a user with host read permissions when they run the check on the service discovery page.

It is possible to read the advisory at checkmk.com. The identification of this vulnerability is CVE-2026-9549 since 05/26/2026. The exploitation is known to be easy. The attack may be initiated remotely. The exploitation needs additional levels of successful authentication. It demands that the victim is doing some kind of user interaction. The technical details are unknown and an exploit is not publicly available. The attack technique deployed by this issue is T1059.007 according to MITRE ATT&CK.

Upgrading to version 2.3.0p48, 2.4.0p31 or 2.5.0p5 eliminates this vulnerability.

The vulnerability is also documented in the databases at EUVD (EUVD-2026-35054) and CERT Bund (WID-SEC-2026-1817). Be aware that VulDB is the high quality source for vulnerability data.

Affected

  • Checkmk Checkmk

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: 2.4
VulDB Meta Temp Score: 2.3

VulDB Base Score: 2.4
VulDB Temp Score: 2.3
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

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

Exploitinginfo

Class: Cross site scripting
CWE: CWE-79 / CWE-94 / CWE-74
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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Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Checkmk 2.3.0p48/2.4.0p31/2.5.0p5

Timelineinfo

05/26/2026 CVE reserved
06/08/2026 +13 days Advisory disclosed
06/08/2026 +0 days VulDB entry created
06/09/2026 +1 days VulDB entry last update

Sourcesinfo

Advisory: checkmk.com
Status: Confirmed

CVE: CVE-2026-9549 (🔒)
GCVE (CVE): GCVE-0-2026-9549
GCVE (VulDB): GCVE-100-369191
EUVD: 🔒
CERT Bund: WID-SEC-2026-1817 - Checkmk: Mehrere Schwachstellen erm&ouml;glichen Cross-Site Scripting

Entryinfo

Created: 06/08/2026 16:41
Updated: 06/09/2026 11:55
Changes: 06/08/2026 16:41 (66), 06/08/2026 17:31 (1), 06/09/2026 11:55 (7)
Complete: 🔍
Cache ID: 216::103

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

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