Resource exhaustion in Broadcom Rabbitmq Server
CVE-2026-66067
RabbitMQ is a messaging and streaming broker. Prior to versions 4.2.7 and 4.3.1, The stream open handler calls only check_vhost_access; it omits the node/vhost/user connection-limit checks that rabbit_reader performs for AMQP. A developer %% FIXME comment at the cited line explicitly acknowledges the gap. No compensating enforcement exists in connection tracking or elsewhere in rabbitmq_stream. An authenticated tenant can fully bypass operator-configured per-user and per-vhost connection caps by connecting via port 5552 instead of 5672. Preconditions include rabbitmq_stream plugin enabled Authenticated stream-protocol credentials Operator relies on per-user/per-vhost connection limits for tenant isolation. This issue is fixed in versions 4.2.7 and 4.3.1.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.004 (38.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 38th percentile — 38.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: +0.001
Affected products
- Broadcom Rabbitmq Server
- Rabbitmq Rabbitmq-Server — versions >= 4.2.0, < 4.2.7, >= 4.3.0, < 4.3.1
Weakness classification (CWE)
References
- github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-hwqx-2gfg-89qf (Vendor Advisory)
- github.com/rabbitmq/rabbitmq-server/releases/tag/v4.2.7 (Release Notes)
- github.com/rabbitmq/rabbitmq-server/releases/tag/v4.3.1 (Release Notes)
Frequently asked questions
- What is CVE-2026-66067?
- CVE-2026-66067 is a medium-severity vulnerability in Broadcom Rabbitmq Server, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 6.5/10. Published 2026-09-23.
- How severe is CVE-2026-66067?
- Medium severity. CVSS v3 base score is 6.5 out of 10.