High7.5Apache Software Foundation

High [CVE-2026-39304] Apache ActiveMQ Client, Apache ActiveMQ Broker, Apache ActiveMQ All, Apache ActiveMQ: Incorrect handling of TLSv1.3 KeyUpdate can be exploited to cause DoS via OOM

This high-severity Apache Software Foundation advisory covers CVE-2026-39304 affecting Apache ActiveMQ, Apache ActiveMQ Client, Apache ActiveMQ Broker.

CVE-2026-39304 Published Apr 10, 2026Updated by vendor Jul 15, 2026

CVE-2026-39304

Affected products & platforms

Apache Software FoundationMessagingActiveMQ

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Summary

Denial of Service via Out of Memory vulnerability in Apache ActiveMQ Client, Apache ActiveMQ Broker, Apache ActiveMQ. ActiveMQ NIO SSL transports do not correctly handle TLSv1.3 handshake KeyUpdates triggered by clients.

This makes it possible for a client to rapidly trigger updates which causes the broker to exhaust all its memory in the SSL engine leading to DoS. Note: TLS versions before TLSv1.3 (such as TLSv1.2) are broken but are not vulnerable to OOM.

Previous TLS versions require a full handshake renegotiation which causes a connection to hang but not OOM. This is fixed as well.

This issue affects Apache ActiveMQ Client: before 5.19.4, from 6.0.0 before 6.2.4; Apache ActiveMQ Broker: before 5.19.4, from 6.0.0 before 6.2.4; Apache ActiveMQ: before 5.19.4, from 6.0.0 before 6.2.4. Users are recommended to upgrade to version 6.2.4 or 5.19.5, which fixes the issue.

Affected products named by the advisory: Apache ActiveMQ All.

Affected versions

Apache ActiveMQ Client before 5.19.4
Apache ActiveMQ Client 6.0.0 before 6.2.4
Apache ActiveMQ Broker before 5.19.4
Apache ActiveMQ Broker 6.0.0 before 6.2.4
Apache ActiveMQ All before 5.19.4
Apache ActiveMQ All 6.0.0 before 6.2.4
Apache ActiveMQ before 5.19.4
Apache ActiveMQ 6.0.0 before 6.2.4

Official advisory · high-confidence parse· fetched 1 month ago·verify at source

Fixed versions

5.19.4
6.2.4

Official advisory · high-confidence parse· fetched 1 month ago·verify at source

Mitigation checklist

Recommended fix / mitigation

Users are recommended to upgrade to version 6.2.4 or 5.19.5, which fixes the issue.

Official advisory · high-confidence parse· fetched 1 month ago·verify at source

Sources

Official and corroborating records used to build this advisory.

CVE.org CNA affected-product recordCVE.org
Structured CNA affected[] data independently confirmed the affected product scope; native advisory content remains authoritative.
CVE Program
NVD discovery recordNVD
Independent discovery and scoring cross-reference. Vendor remediation guidance takes precedence. Discovered from the machine-readable feed https://services.nvd.nist.gov/rest/json/cves/2.0; this link opens the NVD record for CVE-2026-39304 instead of the raw feed document.
NIST National Vulnerability Database

Cross-references

Validate CVE metadata against the authoritative registries.

CVE-2026-39304NVD CVE.org MITRE

Official resources

ASF Security — reporting & CVE process
Official documentation
The Apache Software Foundation's official security page: how ASF CVEs are published and where each project's advisories live.
Apache project downloads (fixed releases)
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