4.8

CVE-2026-9549: checkmk gmbh checkmk Cross-site Scripting

CVSS: 4.8v4.0MediumAnalyzed
AliasesUBUNTU-CVE-2026-9549
Published 08-06-2026Last modified 08-06-2026
Open JSON

Vulnerability summary

CVE-2026-9549 is a medium (CVSS 4.8) Cross-site Scripting vulnerability in checkmk gmbh checkmk. EPSS estimates a 0.24% chance of exploitation in the next 30 days, higher than 14.4% of scored vulnerabilities.

Overall risk
19/100
0100
Low · default modelHow is this calculated?
CVSS score
4.8/10
010
Medium · v4.0 (CVE.org)
EPSS score
0.24%
0%100%
Low · +0.10 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 08-06-2026
    PublishedVulnerability first disclosed.
  2. 08-06-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

5 scores · 3 sources · 2 versions

EPSS trend

Probability

0.24%

Chance of exploitation in the next 30 days

Percentile

14%

Versus all other CVEs

30-day change

+0.10 pp

From 0.14% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.24%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Checkmk1 product
  • checkmkEOL2.2.0 | 2.2.0:b1 | 2.2.0:b2 | 2.2.0:b3 | 2.2.0:b4 | 2.2.0:b5 | 2.2.0:b6 | 2.2.0:b7 | 2.2.0:b8 | 2.2.0:i1 | 2.2.0:p1 | 2.2.0:p10 | 2.2.0:p11 | 2.2.0:p12 | 2.2.0:p13 | 2.2.0:p14 | 2.2.0:p15 | 2.2.0:p16 | 2.2.0:p17 | 2.2.0:p18 | 2.2.0:p19 | 2.2.0:p2 | 2.2.0:p20 | 2.2.0:p21 | 2.2.0:p22 | 2.2.0:p23 | 2.2.0:p24 | 2.2.0:p25 | 2.2.0:p26 | 2.2.0:p27 | 2.2.0:p28 | 2.2.0:p29 | 2.2.0:p3 | 2.2.0:p30 | 2.2.0:p31 | 2.2.0:p32 | 2.2.0:p33 | 2.2.0:p34 | 2.2.0:p35 | 2.2.0:p36 | 2.2.0:p37 | 2.2.0:p38 | 2.2.0:p39 | 2.2.0:p4 | 2.2.0:p40 | 2.2.0:p41 | 2.2.0:p42 | 2.2.0:p43 | 2.2.0:p44 | 2.2.0:p45 | 2.2.0:p46 | 2.2.0:p47 | 2.2.0:p5 | 2.2.0:p6 | 2.2.0:p7 | 2.2.0:p8 | 2.2.0:p9 | 2.3.0 | 2.3.0:b1 | 2.3.0:b2 | 2.3.0:b3 | 2.3.0:b4 | 2.3.0:b5 | 2.3.0:b6 | 2.3.0:p1 | 2.3.0:p10 | 2.3.0:p11 | 2.3.0:p12 | 2.3.0:p13 | 2.3.0:p14 | 2.3.0:p15 | 2.3.0:p16 | 2.3.0:p17 | 2.3.0:p18 | 2.3.0:p19 | 2.3.0:p2 | 2.3.0:p20 | 2.3.0:p21 | 2.3.0:p22 | 2.3.0:p23 | 2.3.0:p24 | 2.3.0:p25 | 2.3.0:p26 | 2.3.0:p27 | 2.3.0:p28 | 2.3.0:p29 | 2.3.0:p3 | 2.3.0:p30 | 2.3.0:p31 | 2.3.0:p32 | 2.3.0:p33 | 2.3.0:p34 | 2.3.0:p35 | 2.3.0:p36 | 2.3.0:p37 | 2.3.0:p38 | 2.3.0:p39 | 2.3.0:p4 | 2.3.0:p40 | 2.3.0:p41 | 2.3.0:p42 | 2.3.0:p43 | 2.3.0:p44 | 2.3.0:p45 | 2.3.0:p46 | 2.3.0:p47 | 2.3.0:p5 | 2.3.0:p6 | 2.3.0:p7 | 2.3.0:p8 | 2.3.0:p9 | 2.4.0 | 2.4.0:b1 | 2.4.0:b2 | 2.4.0:b3 | 2.4.0:b4 | 2.4.0:b5 | 2.4.0:b6 | 2.4.0:p1 | 2.4.0:p10 | 2.4.0:p11 | 2.4.0:p12 | 2.4.0:p13 | 2.4.0:p14 | 2.4.0:p15 | 2.4.0:p16 | 2.4.0:p17 | 2.4.0:p18 | 2.4.0:p19 | 2.4.0:p2 | 2.4.0:p20 | 2.4.0:p21 | 2.4.0:p22 | 2.4.0:p23 | 2.4.0:p24 | 2.4.0:p25 | 2.4.0:p26 | 2.4.0:p27 | 2.4.0:p28 | 2.4.0:p29 | 2.4.0:p3 | 2.4.0:p30 | 2.4.0:p4 | 2.4.0:p5 | 2.4.0:p6 | 2.4.0:p7 | 2.4.0:p8 | 2.4.0:p9 | 2.5.0 | 2.5.0:b1 | 2.5.0:b2 | 2.5.0:b3 | 2.5.0:p1 | 2.5.0:p2 | 2.5.0:p3 | 2.5.0:p4
Checkmk gmbh1 product
  • checkmkEOL≥ 2.5.0, < 2.5.0p5 | ≥ 2.4.0, < 2.4.0p31 | ≥ 2.3.0, < 2.3.0p48 | 2.2.0
Ubuntu1 product
  • check-mkAll versions (No fix recorded)

3 vendors · 3 products

References

3 links