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

HIGH

7.5

CVSS Score

Published: April 10, 2026 at 10:54 AM UTC

Updated: July 15, 2026 at 02:20 AM UTC

4 products affected across 2 vendorsActiveMQApache ActiveMQ BrokerFuse

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Severity

HIGH7.5

Exploit prediction

EPSS 0.9%

SSVC

No known exploit

Description

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

ActiveMQ · Apachemaven

95%

v < 5.19.46.0.0 ≤ v < 6.2.46.0.0

Affected range stops below 5.19.4, so it looks safe — our inference, not a vendor statement

Affected range stops below 6.2.4, so it looks safe — our inference, not a vendor statement

Apache ActiveMQ Broker · Apachemaven

95%

v < 5.19.46.0.0 ≤ v < 6.2.46.0.0

Affected range stops below 5.19.4, so it looks safe — our inference, not a vendor statement

Affected range stops below 6.2.4, so it looks safe — our inference, not a vendor statement

ActiveMQ All · Apachemaven

60%

v < 5.19.46.0.0 ≤ v < 6.2.46.0.0

Affected range stops below 5.19.4, so it looks safe — our inference, not a vendor statement

Affected range stops below 6.2.4, so it looks safe — our inference, not a vendor statement

Fuse · Red Hatrpm

60%

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://activemq.apache.org/security-advisories.data/CVE-2026-39304-announcement.txt

References (5)

Vendor Advisory

Source: cverecord

https://activemq.apache.org/security-advisories.data/CVE-2026-39304-announcement.txt

Mailing ListThird Party Advisory

Source: af854a3a-2127-422b-91ae-364da2661108

http://www.openwall.com/lists/oss-security/2026/04/09/17

Source: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

https://access.redhat.com/security/cve/CVE-2026-39304

Source: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

https://bugzilla.redhat.com/show_bug.cgi?id=2457275

Source: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-39304.json

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHCISA-ADP

Attack Vector: NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: NONE
Integrity: NONE
Availability: HIGH

Vector?

Quick Info

StatusMODIFIED

CWE

CWE-400CWE-770

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