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MEDIUM severity

CVE-2021-4040 — artemis-core-client

MEDIUMFix: apache/activemq-artemis#3871

CVE-2021-4040 is a medium-severity (CVSS 5.3) Uncontrolled Resource Consumption vulnerability in org.apache.activemq:artemis-core-client. A fix is available for org.apache.activemq:artemis-core-client — see the affected versions and patch details below.

org.apache.activemq:artemis-core-client Vulnerable to Out-of-Bounds Write

Also known asGHSA-gf8c-j759-86mg
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 11, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
3.4%probability of exploitation in next 30 days
Lower Risk+0.18%
Lower risk than most CVEs89th percentile — riskier than 89% of all scored CVEsHighest risk
1.98%2.90%3.83%4.76%4.2%3.4%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
☕org.apache.activemq:artemis-core-client

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

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.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
☕Mavenorg.apache.activemq:artemis-core-clientall versions2.19.1org.apache.activemq:artemis-core-client:2.19.1

Affected Products

2 products · 2 configurations
Application
artemisapache
< 2.19.1
range
Application
amq brokerredhat
< 7.10.0
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.activemq:artemis-core-client, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update org.apache.activemq:artemis-core-client to 2.19.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-4040 is resolved across your whole dependency graph.

  3. Workarounds

    Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate
ProductFixed inAdvisory
Red Hat AMQ 7.10.0brokerRHSA-2022:5101

Frequently Asked Questions

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.
O3 Security · Impact-Aware SCA

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CVE-2021-4040: artemis-core-client — Fixed in 2.19.1