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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Apache Software Foundation | Apache ActiveMQ | < 5.19.2, 6.0.0 – < 6.1.9, 6.2.0 – < 6.2.1 | 5.19.2 |
| Apache Software Foundation | Apache ActiveMQ All Module | < 5.19.2, 6.0.0 – < 6.1.9, 6.2.0 – < 6.2.1 | 5.19.2 |
| Apache Software Foundation | Apache ActiveMQ MQTT Module | < 5.19.2, 6.0.0 – < 6.1.9, 6.2.0 – < 6.2.1 | 5.19.2 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 13 | activemq | No fix yet | — |
| Debian 12 | activemq | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | activemq | No fix yet | — |
| Ubuntu 26.04 LTS | activemq | No fix yet | — |
| Ubuntu 25.10 | activemq | No fix yet | — |
| Ubuntu 24.04 LTS | activemq | No fix yet | — |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 22.04 LTS | activemq | No fix yet | — |
| Ubuntu Pro 20.04 LTS | activemq | No fix yet | — |
| Ubuntu Pro 18.04 LTS | activemq | No fix yet | — |
| Ubuntu Pro 16.04 LTS | activemq | No fix yet | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| Maven | org.apache.activemq:activemq-all | < 5.19.2 | 5.19.2 | GHSA-c825-6ph3-4h84 |
| Maven | org.apache.activemq:activemq-all | >= 6.0.0, < 6.1.9 | 6.1.9 | GHSA-c825-6ph3-4h84 |
| Maven | org.apache.activemq:activemq-all | >= 6.2.0, < 6.2.1 | 6.2.1 | GHSA-c825-6ph3-4h84 |
| Maven | org.apache.activemq:activemq-mqtt | < 5.19.2 | 5.19.2 | GHSA-c825-6ph3-4h84 |
| Maven | org.apache.activemq:activemq-mqtt | >= 6.0.0, < 6.1.9 | 6.1.9 | GHSA-c825-6ph3-4h84 |
| Maven | org.apache.activemq:activemq-mqtt | >= 6.2.0, < 6.2.1 | 6.2.1 | GHSA-c825-6ph3-4h84 |
| Maven | org.apache.activemq:apache-activemq | < 5.19.2 | 5.19.2 | GHSA-c825-6ph3-4h84 |
| Maven | org.apache.activemq:apache-activemq | >= 6.0.0, < 6.1.9 | 6.1.9 | GHSA-c825-6ph3-4h84 |
| Maven | org.apache.activemq:apache-activemq | >= 6.2.0, < 6.2.1 | 6.2.1 | GHSA-c825-6ph3-4h84 |
Advisories 2
- WID-SEC-2026-0591 Apache ActiveMQ/Artemis: Mehrere Schwachstellen BSI CERT-Bund (WID) · Sep 22, 2026
- WID-SEC-2026-3043 IBM QRadar SIEM: Mehrere Schwachstellen BSI CERT-Bund (WID) · Sep 17, 2026