Is CVE-2021-40905 in the CISA KEV catalog?

No. CVE-2021-40905 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-40905?

CVE-2021-40905 has a CVSS v3 base score of 8.8 (HIGH).

What is the EPSS score for CVE-2021-40905?

CVE-2021-40905 has an EPSS score of 2.81% (85th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-40905?

Upgrade checkmk to 2.0.0 or later.

CVE & CISA-KEV Catalog

CVE-2021-40905

HIGHEPSS 85th pctl

8.8

CVSS v3

NVD

Description

The web management console of CheckMK Enterprise Edition (versions 1.5.0 to 2.0.0p9) does not properly sanitise the uploading of ".mkp" files, which are Extension Packages, making remote code execution possible. Successful exploitation requires access to the web management interface, either with valid credentials or with a hijacked session of a user with administrator role. NOTE: the vendor states that this is the intended behavior: admins are supposed to be able to execute code in this manner.

CWE-434Unrestricted File Upload

How to fix

Remediation Available

checkmkNVD

Affected:>= 1.5.0, < 2.0.0Fixed in:2.0.0CVE-2021-40905derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionRequired

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Exploit Intelligence

2.81%probability of exploitation in 30 days

85thpercentile

Elevated risk: more likely to be exploited than 85% of all known CVEs.

References

Exploit1

github.com

Product1

checkmk.com

Other references1

docs.checkmk.com

Related Vulnerabilities

Other CWE-434 (Unrestricted File Upload) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2017-12617	High	8.1	100%	KEV	Fix
CVE-2018-15961	Critical	9.8	100%	KEV	-
CVE-2021-31207	Medium	6.6	100%	KEV + Ransom	Fix
CVE-2017-12615	High	8.1	100%	KEV + Ransom	-
CVE-2025-31324	Critical	10.0	99%	KEV + Ransom	-
CVE-2024-50623	Critical	9.8	99%	KEV + Ransom	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-05.