Is CVE-2021-4040 in the CISA KEV catalog?

No. CVE-2021-4040 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-4040?

CVE-2021-4040 has a CVSS v3 base score of 5.3 (MEDIUM).

What is the EPSS score for CVE-2021-4040?

CVE-2021-4040 has an EPSS score of 2.50% (83th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-4040?

Upgrade activemq artemis to 2.19.1 or later. Fixes are available for 3 affected products.

CVE & CISA-KEV Catalog

CVE-2021-4040

MEDIUMEPSS 83th pctl

5.3

CVSS v3

NVD

Description

A flaw was found in AMQ Broker. This issue can cause a partial interruption to the availability of AMQ Broker via an Out of memory (OOM) condition. This flaw allows an attacker to partially disrupt availability to the broker through a sustained attack of maliciously crafted messages. The highest threat from this vulnerability is system availability.

CWE-400Resource Exhaustion CWE-787Out-of-bounds Write

How to fix

Remediation Available

activemq artemisNVD

Affected:< 2.19.1Fixed in:2.19.1CVE-2021-4040derived from NVD

amq brokerNVD

Affected:< 7.10.0Fixed in:7.10.0CVE-2021-4040derived from NVD

artemisNVD

Affected:< 2.19.1Fixed in:2.19.1CVE-2021-4040derived 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 InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityLow

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

Exploit Intelligence

2.50%probability of exploitation in 30 days

83rdpercentile

Elevated risk: more likely to be exploited than 83% of all known CVEs.

References

Patch2

Vendor Advisory2

Related Vulnerabilities

Other CWE-400 (Resource Exhaustion) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2023-44487	High	7.5	100%	KEV	Fix
CVE-2021-44228	Critical	10.0	100%	KEV + Ransom	Fix
CVE-2011-3192	High	7.8	99%	-	Fix
CVE-2019-11478	Medium	5.3	95%	-	Fix
CVE-2024-25617	Medium	5.3	89%	-	Fix
CVE-2018-1000115	High	7.5	89%	-	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 2026-06-15.