RabbitMQ: Pre-auth AMQP 1.0 array32 zero-width element DoS (CVE-2026-66079) | HOL Guard CVE

High · CVSS 8.2CVE-2026-66079

RabbitMQ: Pre-auth AMQP 1.0 array32 zero-width element DoS

Answer in brief

CVE-2026-66079 records a High severity (CVSS 8.2) vulnerability in RabbitMQ: Pre-auth AMQP 1.0 array32 zero-width element DoS. The current sources do not mark it as known exploited. The current feed maps rabbitmq/rabbitmq-server (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 23, 2026Updated Sep 23, 2026Source checked Sep 23, 2026First seen by HOL Sep 23, 2026Material review Sep 23, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 8.2
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 8.2. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps rabbitmq/rabbitmq-server (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
rabbitmq/rabbitmq-servergeneric	>=3.13.0 <3.13.15 \|\| >=4.0.0 <4.0.20 \|\| >=4.1.0 <4.1.11 \|\| >=4.2.0 <4.2.6	3.13.15, 4.0.20, 4.1.11, 4.2.6

Recommended response

Check inventory. Check lockfiles and deployed manifests for rabbitmq/rabbitmq-server.
Review the reported fix. Update rabbitmq/rabbitmq-server to 3.13.15 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 23, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 23, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 23, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.