How severe is CVE-2026-33456?

CVE-2026-33456 has a CVSS 3.x base score of 7.6, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability high.

Is CVE-2026-33456 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (10th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-33456?

CVE-2026-33456 primarily affects Checkmk. In total, 35 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-33456?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-33456 have an EU (EUVD) identifier?

Yes. CVE-2026-33456 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-21344.

When was CVE-2026-33456 published?

CVE-2026-33456 was published on 2026-04-10 and last updated on 2026-06-17.

CVE-2026-33456

CVE-2026-33456 is a high-severity vulnerability in Checkmk with a CVSS 3.x base score of 7.6. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-140.

Key facts

Severity: High (CVSS 3.x base score 7.6)
CVSS v4: 5.1
EPSS exploit prediction: 0% (10th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-21344
Weakness: CWE-140
Affected product: Checkmk
Published: 2026-04-10
Last modified: 2026-06-17

Description

Livestatus injection in the notification test mode in Checkmk <2.5.0b4 and <2.4.0p26 allows an authenticated user with access to the notification test page to inject arbitrary Livestatus commands via a crafted service description.

Frequently asked questions

What is CVE-2026-33456?: Livestatus injection in the notification test mode in Checkmk <2.5.0b4 and <2.4.0p26 allows an authenticated user with access to the notification test page to inject arbitrary Livestatus commands via a crafted service description.
How severe is CVE-2026-33456?: CVE-2026-33456 has a CVSS 3.x base score of 7.6, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability high.
Is CVE-2026-33456 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (10th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-33456?: CVE-2026-33456 primarily affects Checkmk. In total, 35 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-33456?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-33456 have an EU (EUVD) identifier?: Yes. CVE-2026-33456 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-21344.
When was CVE-2026-33456 published?: CVE-2026-33456 was published on 2026-04-10 and last updated on 2026-06-17.

References

https://checkmk.com/werk/17989

Affected products (35)

cpe:2.3:a:checkmk:checkmk:2.4.0:-:*:*:*:*:*:*
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:p1:*:*:*:*:*:*
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: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:2.4.0:p19:*:*:*:*:*:*
cpe:2.3:a:checkmk:checkmk:2.4.0:p2:*:*:*:*:*:*
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:2.4.0:p23:*:*:*:*:*:*
cpe:2.3:a:checkmk:checkmk:2.4.0:p24:*:*:*:*:*:*
cpe:2.3:a:checkmk:checkmk:2.4.0:p25:*:*:*:*:*:*
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: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:2.5.0:b1:*:*:*:*:*:*
cpe:2.3:a:checkmk:checkmk:2.5.0:b2:*:*:*:*:*:*
cpe:2.3:a:checkmk:checkmk:2.5.0:b3:*:*:*:*:*:*

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