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VulnerabilityPublished

CVE-2026-66067: rabbitmq-server · Unthrottled Resource Allocation

Affects rabbitmq-serverSource CVE Database V5

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Not known to be exploited · CVSS 6.0 Medium : upgrade to 4.3.1 or 4.2.7 when convenient.

Data as of 6 Nov 2026, 23:24 UTC

CVSS 4.0 base score
6.0Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.4% chance of exploitation in 30 days – higher than 38% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 4.3.1, 4.2.7
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 23 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 6 Nov 2026.

What to do

Upgrade rabbitmq-server and rabbitmq/rabbitmq-server to 4.3.1 or 4.2.7.

Affected software

ProductAffectedFixed in
rabbitmqrabbitmq-serverAffected
  • >=4.3.0 <4.3.1
Fixed in
  • 4.3.1
rabbitmqrabbitmq-serverAffected
  • >=4.2.0 <4.2.7
Fixed in
  • 4.2.7
GitHubrabbitmq/rabbitmq-serverpkg:github/rabbitmq/rabbitmq-serverOther threatsAffected
  • >=4.2.0 <4.2.7
  • >=4.3.0 <4.3.1
Fixed in
  • 4.2.7
  • 4.3.1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade rabbitmq-server to version 4.2.7 or later, or 4.3.1 or later, where this issue is fixed. No other compensating controls are available as the vulnerability arises from missing enforcement in the stream open handler.

Description

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.

References

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