Apache ActiveMQ is Vulnerable to Integer Overflow or Wraparound
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.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Java / Kotlin (Maven) | org.apache.activemq:activemq-all | < 5.19.2, >= 6.0.0, < 6.1.9, >= 6.2.0, < 6.2.1 | 5.19.2, 6.1.9, 6.2.1 |
| Java / Kotlin (Maven) | org.apache.activemq:activemq-mqtt | < 5.19.2, >= 6.0.0, < 6.1.9, >= 6.2.0, < 6.2.1 | 5.19.2, 6.1.9, 6.2.1 |
| Java / Kotlin (Maven) | org.apache.activemq:apache-activemq | < 5.19.2, >= 6.0.0, < 6.1.9, >= 6.2.0, < 6.2.1 | 5.19.2, 6.1.9, 6.2.1 |
References
- https://nvd.nist.gov/vuln/detail/CVE-2025-66168
- https://activemq.apache.org/security-advisories.data/CVE-2026-40046-announcement.txt
- https://github.com/apache/activemq
- https://lists.apache.org/thread/13n8mkrb2jf2y6yyhpgrkmpqcm7djyto
- https://www.cve.org/CVERecord?id=CVE-2026-40046
- http://www.openwall.com/lists/oss-security/2026/03/03/5
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N- Weakness (CWE)
CWE-190- Platform
- Java / Kotlin (Maven)
- Package
org.apache.activemq:activemq-all, org.apache.activemq:activemq-mqtt, org.apache.activemq:apache-activemq- Disclosed
- 04.03.2026
- Updated
- 11.10.2026 13:20
Sources and licenses
OSV / GitHub Advisory Database - GHSA-c825-6ph3-4h84 - CC BY 4.0
Vulnerability history: org.apache.activemq:activemq-all
All published vulnerabilities of this package (Java / Kotlin (Maven)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 11
- First → latest
- 03.2026 06.2026
- Without a fix
- 0
- Exploited in attacks
- 1
Severity breakdown
- High 6
- Medium 5
Disclosures per year
- 2026: 11
-
Apache ActiveMQ is Vulnerable to Integer Overflow or Wraparound this entry
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