CVE-2026-39304: Denial of Service via Out of Memory in Apache Software Foundation Apache ActiveMQ Client
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.
AI Analysis
Technical Summary
Apache ActiveMQ Client and Broker versions prior to 5.19.4 and from 6.0.0 before 6.2.4 have a denial of service vulnerability due to improper handling of TLSv1.3 handshake KeyUpdates in NIO SSL transports. Clients can rapidly trigger these KeyUpdates, causing the SSL engine to consume all available memory, resulting in an out-of-memory condition and service disruption. TLS versions before 1.3 do not cause out-of-memory but can cause connection hangs due to full handshake renegotiations. The vulnerability is fixed in Apache ActiveMQ versions 5.19.5 and 6.2.4.
Potential Impact
Successful exploitation allows a client to cause the Apache ActiveMQ Broker or Client to exhaust all memory in the SSL engine, leading to denial of service by crashing or hanging the service. This disrupts message brokering and related operations relying on ActiveMQ.
Mitigation Recommendations
Users should upgrade Apache ActiveMQ Client and Broker to version 5.19.5 or 6.2.4 or later, where this vulnerability is fixed. No other mitigation or temporary workaround is specified. Patch status is confirmed by the vendor advisory recommending these versions.
CVE-2026-39304: Denial of Service via Out of Memory in Apache Software Foundation Apache ActiveMQ Client
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.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Apache ActiveMQ Client and Broker versions prior to 5.19.4 and from 6.0.0 before 6.2.4 have a denial of service vulnerability due to improper handling of TLSv1.3 handshake KeyUpdates in NIO SSL transports. Clients can rapidly trigger these KeyUpdates, causing the SSL engine to consume all available memory, resulting in an out-of-memory condition and service disruption. TLS versions before 1.3 do not cause out-of-memory but can cause connection hangs due to full handshake renegotiations. The vulnerability is fixed in Apache ActiveMQ versions 5.19.5 and 6.2.4.
Potential Impact
Successful exploitation allows a client to cause the Apache ActiveMQ Broker or Client to exhaust all memory in the SSL engine, leading to denial of service by crashing or hanging the service. This disrupts message brokering and related operations relying on ActiveMQ.
Mitigation Recommendations
Users should upgrade Apache ActiveMQ Client and Broker to version 5.19.5 or 6.2.4 or later, where this vulnerability is fixed. No other mitigation or temporary workaround is specified. Patch status is confirmed by the vendor advisory recommending these versions.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- apache
- Date Reserved
- 2026-04-06T12:51:57.606Z
- Cvss Version
- null
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 69d8d98b1cc7ad14daad853a
Added to database: 4/10/2026, 11:05:47 AM
Last enriched: 4/10/2026, 11:20:45 AM
Last updated: 4/10/2026, 1:35:46 PM
Views: 5
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