Answer in brief
CVE-2025-66168 records a Medium severity (CVSS 5.4) vulnerability in Apache ActiveMQ is Vulnerable to Integer Overflow or Wraparound. The current sources do not mark it as known exploited. The current feed maps org.apache.activemq:activemq-all (maven), org.apache.activemq:activemq-all (maven), org.apache.activemq:activemq-all (maven), org.apache.activemq:activemq-mqtt (maven) and additional mapped packages. Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 5.4. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps org.apache.activemq:activemq-all (maven), org.apache.activemq:activemq-all (maven), org.apache.activemq:activemq-all (maven), org.apache.activemq:activemq-mqtt (maven) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| org.apache.activemq:activemq-allmaven | >=0 <5.19.2 | 5.19.2 |
| org.apache.activemq:activemq-allmaven | >=6.0.0 <6.1.9 | 6.1.9 |
| org.apache.activemq:activemq-allmaven | >=6.2.0 <6.2.1 | 6.2.1 |
| org.apache.activemq:activemq-mqttmaven | >=0 <5.19.2 | 5.19.2 |
| org.apache.activemq:activemq-mqttmaven | >=6.0.0 <6.1.9 | 6.1.9 |
| org.apache.activemq:activemq-mqttmaven | >=6.2.0 <6.2.1 | 6.2.1 |
| org.apache.activemq:apache-activemqmaven | >=0 <5.19.2 | 5.19.2 |
| org.apache.activemq:apache-activemqmaven | >=6.0.0 <6.1.9 | 6.1.9 |
| org.apache.activemq:apache-activemqmaven | >=6.2.0 <6.2.1 | 6.2.1 |
Published upstream
Mar 4, 2026
Evidence: source:osv:source_dates:source-dates:recordSource modified
Sep 10, 2026
Evidence: source:osv:source_dates:source-dates:recordFirst seen by HOL
Sep 10, 2026
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.
Quoted source text, attributed separately from HOL analysis.