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🛡️ CVE-2025-66168 — activemq

🟠 CVSS 8.0 — High ✅ No Known Exploit CWE-190 OSV
8.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

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

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.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality low, integrity low, availability none.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: Low — an ordinary user account is enough.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: Low — limited, and the attacker does not choose what is affected.
  • Integrity impact: Low — limited, and the attacker does not choose what is affected.
  • Availability impact: None.

Weakness class

CVE-2025-66168 is classified as CWE-190: Integer Overflow or Wraparound. Arithmetic produces a value too large for its type and wraps around, so a later size or bounds check passes when it should not.

Affected software

CVE-2025-66168 is recorded against 4 packages.

  • activemq
  • org.apache.activemq:activemq-all (from 6.2.0 up to 6.2.1)
  • org.apache.activemq:activemq-mqtt (from 6.2.0 up to 6.2.1)
  • org.apache.activemq:apache-activemq (from 6.2.0 up to 6.2.1)

Timeline and source

Published on 6 March 2026 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

www.openwall.com (Web)
lists.apache.org (Web)
nvd.nist.gov (Web)
activemq.apache.org (Web)
www.cve.org (Web)

Other advisories for this package

activemq has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-190: Integer Overflow or Wraparound) in other software:

CVE-2025-66168 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity HIGH
CVSS Score 8.0
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
CWE CWE-190
Public Exploit ✅ No
Source OSV
Published 2026-03-06
Updated 2026-08-20
Modified 2026-06-17
Fix URL N/A

Affected Packages

Software From version Fixed in
activemq — —
org.apache.activemq:activemq-all 6.2.0 6.2.1
org.apache.activemq:activemq-mqtt 6.2.0 6.2.1
org.apache.activemq:apache-activemq 6.2.0 6.2.1

Site Security Check

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