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Fencer Vulns
medium 5.4

CVE-2025-66168 json

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

published 2026-03-04 8 mo ago modified 2026-09-10 1 mo ago also BIT-activemq-2025-66168 , EUVD-2025-208266 , GHSA-c825-6ph3-4h84

cvss
5.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.9%
EPSS 0.9% chance of exploitation in 30 days, percentile 59%
public exploits
0
none known

Summary

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.

Patch / fix

  • maven org.apache.activemq:apache-activemq 5.19.2, 6.1.9, 6.2.1
  • maven org.apache.activemq:activemq-all 5.19.2, 6.1.9, 6.2.1
  • maven org.apache.activemq:activemq-mqtt 5.19.2, 6.1.9, 6.2.1
  • bitnami activemq 5.19.2, 6.1.9, 6.2.1
  • Apache Software Foundation Apache ActiveMQ 5.19.2, 6.1.9, 6.2.1
  • Apache Software Foundation Apache ActiveMQ All Module 5.19.2, 6.1.9, 6.2.1
  • Apache Software Foundation Apache ActiveMQ MQTT Module 5.19.2, 6.1.9, 6.2.1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-66168 updated cvss 5.4

org.apache.activemq/apache-activemq: org.apache.activemq/activemq-all: org.apache.activemq/activemq-mqtt: Apache ActiveMQ: Unexpected behavior due to integer overflow in MQTT packet decoding

  • Red Hat Fuse 7 activemq-all, activemq-mqtt Red Hat JBoss Enterprise Application Platform 7 activemq-mqtt
    affected: workaround, no fix available “Fix deferred”
  • Red Hat JBoss Enterprise Application Platform 8 activemq-mqtt
    affected: workaround, no fix planned “Will not fix”
  • Red Hat JBoss Enterprise Application Platform Expansion Pack activemq-mqtt
    affected: workaround, no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
8 mo ago

Exploit prediction

0.87% chance of exploitation in the next 30 days, higher than 59% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
GitHub 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
NVD 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
OSV 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
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
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
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
bitnami 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

Affected products

  • Apache Software Foundation Apache ActiveMQ
  • Apache Software Foundation Apache ActiveMQ All Module
  • Apache Software Foundation Apache ActiveMQ MQTT Module

Classification

Weakness
  • CWE-190 Integer Overflow or Wraparound

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.