Riskcovery

CVE-2025-66168

Apache ActiveMQ, Apache ActiveMQ All Module, Apache ActiveMQ MQTT Module: MQTT control packet remaining length field is not properly validated

State
Published
Severity
5.4 Medium
Published
Mar 4, 2026
Updated
Apr 10, 2026
Reserved
Nov 21, 2025

Read the record on cve.org

Description

WARNING:

Users of 6.x should upgrade to 6.2.4 or later as the fix was missed in previous 6.x releases.

See the  following for more details: https://activemq.apache.org/security-advisories.data/CVE-2026-40046-announcement.txt https://www.cve.org/CVERecord?id=CVE-2026-40046

Original Report:

Apache ActiveMQ does not properly validate the remaining length field which may lead to an overflow during the decoding of malformed packets. When this integer overflow occurs, ActiveMQ may incorrectly compute the total Remaining Length and subsequently misinterpret the payload as multiple MQTT control packets which makes the broker susceptible to unexpected behavior when interacting with non-compliant clients. This behavior violates the MQTT v3.1.1 specification, which restricts Remaining Length to a maximum of 4 bytes. The scenario occurs on established connections after the authentication process. Brokers that are not enabling mqtt transport connectors are not impacted.

This issue affects Apache ActiveMQ: before 5.19.2, 6.0.0 to 6.1.8, and 6.2.0

Users are recommended to upgrade to version 5.19.2, 6.1.9, or 6.2.1, which fixes the issue.

Scores

CVSSScoreVectorSource
3.15.4 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:Napache

Weaknesses

  • CWE-190 Integer Overflow or Wraparound

Affected Products

ProductVersions
Apache ActiveMQApache Software Foundation
  • before 5.19.2Affected
  • 6.0.0 to before 6.1.9Affected
  • 6.2.0 to before 6.2.1Affected
Apache ActiveMQ All ModuleApache Software Foundation
  • before 5.19.2Affected
  • 6.0.0 to before 6.1.9Affected
  • 6.2.0 to before 6.2.1Affected
Apache ActiveMQ MQTT ModuleApache Software Foundation
  • before 5.19.2Affected
  • 6.0.0 to before 6.1.9Affected
  • 6.2.0 to before 6.2.1Affected

References

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