4.8
MEDIUM
CVSS 4.0
CVE-2026-9549
Fix XSS in service discovery active check output
Overview
Description
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.
Details
INFO
Published Date :
June 8, 2026, 1:16 p.m.
Last Modified :
June 8, 2026, 3:53 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Scoring
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework
for assessing the severity of vulnerabilities in software and systems.
We collect and displays CVSS scores from various sources for each CVE.
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
Update Checkmk to a patched version to fix stored cross-site scripting.
- Update Checkmk to version 2.5.0p5 or later.
- Update Checkmk to version 2.4.0p31 or later.
- Update Checkmk to version 2.3.0p48 or later.
- Update to a supported 2.2.0 version.
References
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-9549.
| URL | Resource |
|---|---|
| https://checkmk.com/werk/17993 | Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-9549 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-9549
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-9549 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-9549 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Jun. 08, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N Added CPE Configuration OR *cpe:2.3:a:checkmk:checkmk:2.2.0:i1:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:b2:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:b1:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:b3:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:-:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:b4:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:b5:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:b6:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:b7:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:b8:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p1:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p2:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p3:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p4:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p6:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p7:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p5:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p8:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p9:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p10:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p11:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p12:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p13:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p14:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p15:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p16:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p17:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p1:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p2:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p3:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p4:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p5:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p6:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p7:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p8:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p9:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p19:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p20:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p21:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p22:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p23:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p24:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p25:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p26:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p27:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p28:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p29:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p30:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p18:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p10:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p31:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:-:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p13:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p11:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p12:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p15:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p14:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p33:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p17:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p16:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p35:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p34:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p32:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p38:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p37:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p36:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:b2:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:b3:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:b1:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:b4:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:b5:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:b6:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p20:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p21:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p18:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p19:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p22:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p39:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p23:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p24:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p25:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p26:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p40:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p27:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p28:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p29:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p41:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p30:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p31:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:b1:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:b2:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:b3:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:b4:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:b5:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:b6:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:-:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p42:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p43:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p32:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p33:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p34:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p1:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p2:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p3:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p4:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p5:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:*:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p10:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p11:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p12:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p13:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p14:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p15:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p6:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p7:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p8:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p9:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p35:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p36:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p37:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p38:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p39:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p40:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p44:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p45:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p46:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.2.0:p47:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p16:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p17:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p18:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p41:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p42:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p19:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p20:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p21:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p22:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.5.0:b1:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p23:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p24:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p43:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p44:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p45:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.5.0:b2:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p46:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p25:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.5.0:b3:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p26:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p27:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p28:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.3.0:p47:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p29:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.4.0:p30:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.5.0:-:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.5.0:p1:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.5.0:p2:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.5.0:p3:*:*:*:*:*:* *cpe:2.3:a:checkmk:checkmk:2.5.0:p4:*:*:*:*:*:* Added Reference Type Checkmk GmbH: https://checkmk.com/werk/17993 Types: Vendor Advisory -
New CVE Received by [email protected]
Jun. 08, 2026
Action Type Old Value New Value Added Description 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. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:H/UI:P/VC:N/VI:L/VA:N/SC:N/SI:L/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 Added CWE CWE-79 Added Reference https://checkmk.com/werk/17993
EPSS is a daily estimate of the probability of exploitation activity
being observed over the next 30 days. Following chart shows the EPSS
score history of the vulnerability.