Rabbitmq server: RabbitMQ is a messaging and streaming broker. (CVE-2026-66067)
Description
RabbitMQ versions prior to 4.2.7 and 4.3.1 contain a vulnerability in the stream open handler that allows authenticated tenants to bypass operator-configured per-user and per-vhost connection limits by connecting via port 5552 instead of the standard AMQP port 5672. This occurs because the stream open handler only checks vhost access but omits node/vhost/user connection-limit checks enforced for AMQP connections. The issue is fixed in versions 4.2.7 and 4.3.1.
CVSS v4.0
Affected software
pkg:deb/ubuntu/rabbitmq-server?arch=source&distro=esm-infra-legacy/xenialpkg:deb/ubuntu/rabbitmq-server?arch=source&distro=esm-infra/bionicpkg:deb/ubuntu/rabbitmq-server?arch=source&distro=esm-infra/focalpkg:deb/ubuntu/rabbitmq-server?arch=source&distro=jammypkg:deb/ubuntu/rabbitmq-server?arch=source&distro=noblepkg:deb/ubuntu/rabbitmq-server?arch=source&distro=resoluteRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The RabbitMQ messaging and streaming broker has a vulnerability identified as CVE-2026-66067 affecting versions prior to 4.2.7 and 4.3.1. The stream open handler calls only check_vhost_access and omits connection-limit checks that are performed for AMQP connections. Consequently, an authenticated tenant can bypass per-user and per-vhost connection caps by connecting through port 5552 (stream protocol) instead of port 5672 (AMQP). This bypass undermines operator-configured connection limits intended for tenant isolation. The vulnerability requires the rabbitmq_stream plugin to be enabled and valid authenticated stream-protocol credentials. The issue is resolved in versions 4.2.7 and 4.3.1.
Potential Impact
Authenticated tenants can bypass operator-configured per-user and per-vhost connection limits, potentially allowing them to exceed connection caps intended to enforce tenant isolation. This could lead to resource exhaustion or denial of service conditions affecting multi-tenant environments relying on these limits.
Mitigation Recommendations
Upgrade RabbitMQ to versions 4.2.7 or 4.3.1 or later, where this vulnerability is fixed. Ensure the rabbitmq_stream plugin is updated accordingly. No other compensating controls exist, so patching is the primary mitigation.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- UBUNTU-CVE-2026-66067
- Osv Schema Version
- 1.7.0
- Ecosystems
- ["Ubuntu:Pro:16.04:LTS","Ubuntu:Pro:18.04:LTS","Ubuntu:Pro:20.04:LTS","Ubuntu:22.04:LTS","Ubuntu:24.04:LTS","Ubuntu:26.04:LTS"]
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6ad3f5b12cdf04f65666282a
Added to database: 10/17/2026, 22:24:49 UTC
Last enriched: 10/18/2026, 00:10:21 UTC
Last updated: 10/18/2026, 00:10:21 UTC
Views: 2
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