CVE-2026-39304 PUBLISHED

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

Assigner: apache
Reserved: 06.04.2026 Published: 10.04.2026 Updated: 10.04.2026

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.

Product Status

Vendor Apache Software Foundation
Product Apache ActiveMQ Client
Versions Default: unaffected
  • affected from 0 to 5.19.4 (excl.)
  • affected from 6.0.0 to 6.2.4 (excl.)
Vendor Apache Software Foundation
Product Apache ActiveMQ Broker
Versions Default: unaffected
  • affected from 0 to 5.19.4 (excl.)
  • affected from 6.0.0 to 6.2.4 (excl.)
Vendor Apache Software Foundation
Product Apache ActiveMQ All
Versions Default: unaffected
  • affected from 0 to 5.19.4 (excl.)
  • affected from 6.0.0 to 6.2.4 (excl.)
Vendor Apache Software Foundation
Product Apache ActiveMQ
Versions Default: unaffected
  • affected from 0 to 5.19.4 (excl.)
  • affected from 6.0.0 to 6.2.4 (excl.)

References

Problem Types

  • Denial of Service via Out of Memory