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VulnerabilityPublished Updated

CVE-2026-66079: rabbitmq-server · Unthrottled Resource Allocation

Affects rabbitmq-serverSource CVE Database V5

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Not known to be exploited · CVSS 8.2 High · fixed in 4.2.6 : patch rabbitmq-server soon.

Data as of 6 Nov 2026, 23:24 UTC

CVSS 4.0 base score
8.2High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 24% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 4.2.6, 4.1.11, 4.0.20 +1
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/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 to 4.2.6, 4.1.11, 4.0.20 or 3.13.15.

Affected software

ProductAffectedFixed in
rabbitmqrabbitmq-serverAffected
  • >=4.2.0 <4.2.6
Fixed in
  • 4.2.6
rabbitmqrabbitmq-serverAffected
  • >=4.1.0 <4.1.11
Fixed in
  • 4.1.11
rabbitmqrabbitmq-serverAffected
  • >=4.0.0 <4.0.20
Fixed in
  • 4.0.20
rabbitmqrabbitmq-serverAffected
  • >=3.13.0 <3.13.15
Fixed in
  • 3.13.15
GitHubrabbitmq/rabbitmq-serverpkg:github/rabbitmq/rabbitmq-serverOther threatsAffected
  • >=3.13.0 <=3.13.14
  • >=4.0.0 <=4.0.19
  • >=4.1.0 <=4.1.10
  • >=4.2.0 <=4.2.5
Fixed in–

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

AI-suggested

This vulnerability is fixed in rabbitmq-server versions 3.13.15, 4.0.20, 4.1.11, and 4.2.6. Users should upgrade to these or later versions to remediate the issue. No additional mitigations are indicated in the advisory.

Description

RabbitMQ is a messaging and streaming broker. Prior to versions 3.13.15, 4.0.20, 4.1.11, and 4.2.6, parse_array_primitive/2 for constructor 0x45 (list0) returns an element with byte-width B = 0. The enclosing array32 parser at line 148 reads a 4-byte Count from the wire and loops Count times consuming B bytes each , with B = 0, no input is consumed and the loop builds a list of Count empty elements bounded only by the 32-bit field. The SASL-mechanisms / SASL-init frame is parsed by amqp10_framing:decode_bin/1 from rabbit_amqp_reader.erl:412 before authentication completes. The pre-auth incoming_max_frame_size (default 8192 bytes) caps the frame, not the Count field, so a 19-byte payload with Count = 0xFFFFFFFF is accepted. No max_heap_size is set on the reader process. An unauthenticated network attacker can crash any RabbitMQ node that has the AMQP 1.0 listener enabled (default port 5672) by sending a single ~19-byte frame. The reader process attempts to build a list of ~4 billion empty elements, exhausting heap memory and terminating the Erlang VM. All tenants and protocols on the node lose service. Preconditions include Network reachability to the AMQP listener (port 5672, enabled by default) No authentication required. This issue is fixed in versions 3.13.15, 4.0.20, 4.1.11, and 4.2.6.

References

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