CVE-2026-40046
Description
A flaw was found in Apache ActiveMQ, Apache ActiveMQ All and Apache ActiveMQ MQTT. The fix for CVE-2025-66168 was not applied for 6.0.0+ versions. This exposed the underlying integer overflow/wraparound vulnerability when handling MQTT control packets, causing the broker to misinterpret payloads and leading to unexpected behavior when interacting with non-compliant clients.
Statement
This issue specifically affects Apache ActiveMQ, Apache ActiveMQ All and Apache ActiveMQ MQTT versions from 6.0.0 before 6.2.4. These versions are not shipped in any Red Hat product.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.4 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | Low | N/A | None |
| Integrity Impact | Low | N/A | None |
| Availability Impact | None | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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