SB2026041072 - Multiple vulnerabilities in Apache ActiveMQ

Description

This security bulletin contains information about 2 secuirty vulnerabilities.

1) Improper Check or Handling of Exceptional Conditions (CVE-ID: CVE-2026-39304)

The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to improper handling of TLSv1.3 KeyUpdate messages in ActiveMQ NIO SSL transports when processing client-triggered TLSv1.3 handshake KeyUpdates. A remote attacker can rapidly trigger KeyUpdate messages to cause a denial of service.

Only TLSv1.3 is vulnerable to out-of-memory exhaustion; earlier TLS versions may cause a connection hang instead.

2) Integer overflow (CVE-ID: CVE-2026-40046)

The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to integer overflow or wraparound in the MQTT control packet remaining length field handling when parsing MQTT control packets. A remote attacker can send a specially crafted MQTT control packet to cause a denial of service.

Remediation

Install update from vendor's website.

References

• https://lists.apache.org/api/email.lua?id=v8yspozbn9gggnd63jvmmvyoyor7k6zh
• https://lists.apache.org/api/email.lua?id=4qojjf66mg215hchnjyjmnqknq60wqgf