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Apache ActiveMQ is Vulnerable to Integer Overflow or Wraparound

Moderate severity GitHub Reviewed Published Mar 4, 2026 to the GitHub Advisory Database • Updated Mar 4, 2026

Package

maven org.apache.activemq:activemq-all (Maven)

Affected versions

< 5.19.2
>= 6.0.0, < 6.1.9
= 6.2.0

Patched versions

5.19.2
6.1.9
6.2.1
maven org.apache.activemq:activemq-mqtt (Maven)
< 5.19.2
>= 6.0.0, < 6.1.9
= 6.2.0
5.19.2
6.1.9
6.2.1
maven org.apache.activemq:apache-activemq (Maven)
< 5.19.2
>= 6.0.0, < 6.1.9
= 6.2.0
5.19.2
6.1.9
6.2.1

Description

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.

References

Published by the National Vulnerability Database Mar 4, 2026
Published to the GitHub Advisory Database Mar 4, 2026
Reviewed Mar 4, 2026
Last updated Mar 4, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(31st percentile)

Weaknesses

Integer Overflow or Wraparound

The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number. Learn more on MITRE.

CVE ID

CVE-2025-66168

GHSA ID

GHSA-c825-6ph3-4h84

Source code

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