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NVD / CVE Program· CNA apache

CVE-2025-66168: Apache ActiveMQ, Apache ActiveMQ All Module, Apache ActiveMQ MQTT Module: MQTT control packet remaining length field is not properly validated

Noroxi assessment

Priority: Monitor (action score 35/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.87% (FIRST EPSS); higher than 59.1% of all records.
  • Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: 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.
  • Severity is disputed: the assigning authority (CNA) scores it 5.4, NVD 8.8.

Low priority for now. Upgrade to 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 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

HighCVSS 8.8 · v3.1—No exploit Fix available
Published
Mar 4, 2026
Updated
Jun 17, 2026
EPSS
0.8% · 59th percentile

Report tools

JSON

Action score

35

Monitor

Low priority for now.

CVSS
35 / 40 · 8.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.8%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
8.8
CNA · apache
5.4
3.4 point gap

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2025-66168

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
apacheactivemq

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • apache activemqbefore 5.19.2
  • apache activemq6.0.0 and later · up to 6.1.8 inclusive
  • apache activemq6.2.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (apache). Independent of NVD's CPE analysis and usually ahead of it.

  • Apache Software Foundation Apache ActiveMQ

    • before 5.19.2affected · semver
    • 6.0.0 and later · before 6.1.9affected · semver
    • 6.2.0 and later · before 6.2.1affected · semver

  • Apache Software Foundation Apache ActiveMQ All Module

    • before 5.19.2affected · semver
    • 6.0.0 and later · before 6.1.9affected · semver
    • 6.2.0 and later · before 6.2.1affected · semver

  • Apache Software Foundation Apache ActiveMQ MQTT Module

    • before 5.19.2affected · semver
    • 6.0.0 and later · before 6.1.9affected · semver
    • 6.2.0 and later · before 6.2.1affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12activemqfrom 0—
Mavenorg.apache.activemq:activemq-allfrom 6.0.0 · before 6.1.96.1.9
Mavenorg.apache.activemq:activemq-allfrom 6.2.0 · before 6.2.16.2.1
Mavenorg.apache.activemq:activemq-allbefore 5.19.25.19.2
Mavenorg.apache.activemq:activemq-mqttfrom 6.0.0 · before 6.1.96.1.9
Mavenorg.apache.activemq:activemq-mqttfrom 6.2.0 · before 6.2.16.2.1
Mavenorg.apache.activemq:activemq-mqttbefore 5.19.25.19.2
Mavenorg.apache.activemq:apache-activemqfrom 6.0.0 · before 6.1.96.1.9
Mavenorg.apache.activemq:apache-activemqfrom 6.2.0 · before 6.2.16.2.1
Mavenorg.apache.activemq:apache-activemqbefore 5.19.25.19.2

Same product

apache: all records

Other highest-scoring records for the same primary product.

  • CVE-2023-46604Apache ActiveMQ, Apache ActiveMQ Legacy OpenWire Module: Unbounded deserialization causes ActiveMQ to be vulnerable to a remote code execution (RCE) attackKEV
    99Now
  • CVE-2016-3088The Fileserver web application in Apache ActiveMQ 5.x before 5.14.0 allows remote attackers to upload and execute arbitrary files via an HTTKEV
    99Now
  • CVE-2026-34197Apache ActiveMQ Broker, Apache ActiveMQ All, Apache ActiveMQ: Authenticated users could perform RCE via Jolokia MBeansKEV
    94Now

Published before and after this one in the same product

  • ← EarlierCVE-2024-32114May 2, 2024 · Apache ActiveMQ: Jolokia and REST API were not secured with default configuration
    37Monitor
  • ← EarlierCVE-2025-27533May 7, 2025 · Apache ActiveMQ: Unchecked buffer length can cause excessive memory allocation
    30Monitor
  • Later →CVE-2026-33227Apr 7, 2026 · Apache ActiveMQ Client, Apache ActiveMQ Broker, Apache ActiveMQ All, Apache ActiveMQ Web, Apache ActiveMQ: Improper Limitation of a Pathname to a Restricted Cla
    17Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Apache Software Foundation Apache ActiveMQ5.19.2Vendor (CNA)
Apache Software Foundation Apache ActiveMQ6.1.9Vendor (CNA)
Apache Software Foundation Apache ActiveMQ6.2.1Vendor (CNA)
Apache Software Foundation Apache ActiveMQ All Module5.19.2Vendor (CNA)
Apache Software Foundation Apache ActiveMQ All Module6.1.9Vendor (CNA)
Apache Software Foundation Apache ActiveMQ All Module6.2.1Vendor (CNA)
Apache Software Foundation Apache ActiveMQ MQTT Module5.19.2Vendor (CNA)
Apache Software Foundation Apache ActiveMQ MQTT Module6.1.9Vendor (CNA)
Apache Software Foundation Apache ActiveMQ MQTT Module6.2.1Vendor (CNA)
Maven:org.apache.activemq:activemq-all5.19.2Package registry (OSV)
Maven:org.apache.activemq:activemq-all6.1.9Package registry (OSV)
Maven:org.apache.activemq:activemq-all6.2.1Package registry (OSV)
Maven:org.apache.activemq:activemq-mqtt5.19.2Package registry (OSV)
Maven:org.apache.activemq:activemq-mqtt6.1.9Package registry (OSV)
Maven:org.apache.activemq:activemq-mqtt6.2.1Package registry (OSV)
Maven:org.apache.activemq:apache-activemq5.19.2Package registry (OSV)
Maven:org.apache.activemq:apache-activemq6.1.9Package registry (OSV)
Maven:org.apache.activemq:apache-activemq6.2.1Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-190 · Integer Overflow or Wraparound

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (3 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records