6.3

CVE-2026-2859: checkmk gmbh checkmk Observable Response Discrepancy

CVSS: 6.3v4.0MediumAnalyzed
AliasesUBUNTU-CVE-2026-2859
Published 13-03-2026Last modified 13-03-2026
Open JSON

Vulnerability summary

CVE-2026-2859 is a medium (CVSS 6.3) Observable Response Discrepancy vulnerability in checkmk gmbh checkmk. EPSS estimates a 0.33% chance of exploitation in the next 30 days, higher than 24.8% of scored vulnerabilities.

Overall risk
25/100
0100
Medium · default modelHow is this calculated?
CVSS score
6.3/10
010
Medium · v4.0 (CVE.org)
EPSS score
0.33%
0%100%
Low · +0.14 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 13-03-2026
    PublishedVulnerability first disclosed.
  2. 13-03-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

5 scores · 3 sources · 2 versions

EPSS trend

Probability

0.33%

Chance of exploitation in the next 30 days

Percentile

25%

Versus all other CVEs

30-day change

+0.14 pp

From 0.19% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.33%

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: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:p3 | 2.4.0:p4 | 2.4.0:p5 | 2.4.0:p6 | 2.4.0:p7 | 2.4.0:p8 | 2.4.0:p9
Checkmk gmbh1 product
  • checkmkEOL≥ 2.4.0, < 2.4.0p23 | ≥ 2.3.0, < 2.3.0p43 | 2.2.0
Ubuntu1 product
  • check-mkAll versions (No fix recorded)

3 vendors · 3 products

References

3 links