CVE-2026-67414: RabbitMQ AMQP 1.0 parser: amplification memory-exhaustion DoS via zero-width array aggregation
RabbitMQ is a messaging and streaming broker. From 4.0.0 until 4.0.24, 4.1.15, 4.2.10, and 4.3.4, deps/amqp10common/src/amqp10binaryparser.erl materializes each element of AMQP 1.0 arrays whose shared constructor has zero width, while limiting only the number of elements in each array and not the aggregate arrays in a frame. After completing SASL authentication, a low-privilege client can send an ordinary frame containing many individually permitted arrays, causing a small frame to expand into a very large reader-process heap before later frame validation or authorization. Because deps/rabbit/src/rabbitamqpreader.erl clears the pre-authentication maxheapsize guard after login, repeated or concurrent frames can trigger the node-wide memory alarm, block publishers, or exhaust broker memory. This issue is fixed in versions 4.0.24, 4.1.15, 4.2.10, and 4.3.4.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
RabbitMQto a version that resolves this vulnerability.Fixed in 4.0.24 - Upgrade
Upgrade
RabbitMQto a version that resolves this vulnerability.Fixed in 4.1.15 - Upgrade
Upgrade
RabbitMQto a version that resolves this vulnerability.Fixed in 4.2.10 - Upgrade
Upgrade
RabbitMQto a version that resolves this vulnerability.Fixed in 4.3.4
Event History
Frequently Asked Questions
Who can exploit this issue?
A low-privilege client that has completed SASL authentication can exploit it. The attack does not require authorization to perform the later operation represented by the frame, because memory expansion occurs before later frame validation or authorization.
Are unauthenticated clients affected?
The described attack path applies after SASL authentication. RabbitMQ retains a pre-authentication max_heap_size guard before login, but clears that guard after login.
What is the operational impact of exploitation?
Repeated or concurrent malicious frames can trigger the node-wide memory alarm, which can block publishers, or can exhaust broker memory. A small AMQP 1.0 frame can cause a very large heap allocation in the reader process.
Which versions contain the fix?
The issue is fixed in RabbitMQ 4.0.24, 4.1.15, 4.2.10, and 4.3.4. The affected ranges begin at 4.0.0 and extend up to, but do not include, those fixed releases in each listed version line.