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
This vulnerability affects Apache ActiveMQ Client, Broker, and Apache ActiveMQ in versions prior to 5.19.4 and from 6.0.0 up to but not including 6.2.4. The root cause is that the NIO SSL transport does not correctly handle TLSv1.3 handshake KeyUpdates triggered by clients. An attacker can exploit this by rapidly triggering TLSv1.3 KeyUpdates, causing the broker's SSL engine to consume excessive memory, leading to an out-of-memory condition and denial of service. TLS versions before 1.3 are not vulnerable to the out-of-memory issue but can cause connection hangs due to full handshake renegotiations. The Apache Software Foundation recommends upgrading to versions 6.2.4 or 5.19.5 where this issue is resolved.
Potential Impact
Successful exploitation results in a denial of service condition by exhausting the broker's memory resources, causing service disruption. There is no impact on confidentiality or integrity reported. The vulnerability is remotely exploitable without authentication.
Mitigation Recommendations
Users should upgrade Apache ActiveMQ Client, Broker, and Apache ActiveMQ to versions 6.2.4 or 5.19.5 or later, which contain fixes for this vulnerability. No other mitigation or temporary workaround is specified. Patch status is confirmed by the vendor advisory recommending these version upgrades.
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
This vulnerability affects Apache ActiveMQ Client, Broker, and Apache ActiveMQ in versions prior to 5.19.4 and from 6.0.0 up to but not including 6.2.4. The root cause is that the NIO SSL transport does not correctly handle TLSv1.3 handshake KeyUpdates triggered by clients. An attacker can exploit this by rapidly triggering TLSv1.3 KeyUpdates, causing the broker's SSL engine to consume excessive memory, leading to an out-of-memory condition and denial of service. TLS versions before 1.3 are not vulnerable to the out-of-memory issue but can cause connection hangs due to full handshake renegotiations. The Apache Software Foundation recommends upgrading to versions 6.2.4 or 5.19.5 where this issue is resolved.
Potential Impact
Successful exploitation results in a denial of service condition by exhausting the broker's memory resources, causing service disruption. There is no impact on confidentiality or integrity reported. The vulnerability is remotely exploitable without authentication.
Mitigation Recommendations
Users should upgrade Apache ActiveMQ Client, Broker, and Apache ActiveMQ to versions 6.2.4 or 5.19.5 or later, which contain fixes for this vulnerability. No other mitigation or temporary workaround is specified. Patch status is confirmed by the vendor advisory recommending these version upgrades.
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: 4/17/2026, 12:25:17 PM
Last updated: 5/25/2026, 8:59:12 PM
Views: 71
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