# CVE-2026-67235: RabbitMQ: AMQP 0-9-1 body assembly never validates accumulated size

CVE-2026-67235 is fixed in rabbitmq-server on 1 platform, first by rabbitmq-server 4.0.5-10ubuntu5.2, released September 25, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-67235
- Priority: Routine
- CVSS: 6.5 (Moderate)
- EPSS: 0.0030
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 23, 2026
- Weakness: Allocation of Resources Without Limits or Throttling
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-67235

## Description

RabbitMQ is a messaging and streaming broker. Prior to versions 4.3.0, 4.2.6, 4.1.11, 4.0.20, and 3.13.15, The content-header BodySize (a uint64) was stored without validation against max_message_size. The size check ran only when assembly completed. By declaring body_size = 2^63-1 and then streaming fragments, a client ensured that check_msg_size never fired, so the accumulated body size went unbounded. A reader process accumulates memory until the memory alarm fires, degrading all publishers cluster-wide, or until the node runs out of memory. The memory alarm provides only partial mitigation, since it is reactive rather than preventive. AMQP 0-9-1 is the most widely used protocol, and any publisher can trigger this condition. Preconditions include Any authenticated AMQP 0-9-1 client with publish permission can exploit this.. This issue is fixed in versions 4.3.0, 4.2.6, 4.1.11, 4.0.20, and 3.13.15.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | rabbitmq-server Debian 14 | 4.3.0-2 | [DEBIAN-CVE-2026-67235](https://patchblox.com/security/data/fix/linux/debian-cve-2026-67235.md) | Sep 25, 2026 |
| Linux | rabbitmq-server Ubuntu 18.04.6 LTS (bionic) | 3.6.10-1ubuntu0.5+esm1 | [rabbitmq-server 3.6.10-1ubuntu0.5+esm1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-rabbitmq-server-3.6.10-1ubuntu0.5-esm1.md) | Oct 19, 2026 |
| Linux | rabbitmq-server Ubuntu 20.04 LTS (focal) | 3.8.3-0ubuntu0.3+esm2 | [rabbitmq-server 3.8.3-0ubuntu0.3+esm2](https://patchblox.com/security/data/fix/linux/ubuntu-focal-rabbitmq-server-3.8.3-0ubuntu0.3-esm2.md) | Oct 19, 2026 |
| Linux | rabbitmq-server Ubuntu 22.04.1 LTS (jammy) | 3.9.27-0ubuntu0.6 | [rabbitmq-server 3.9.27-0ubuntu0.6](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-rabbitmq-server-3.9.27-0ubuntu0.6.md) | Oct 19, 2026 |
| Linux | rabbitmq-server Ubuntu 24.04.5 LTS (noble) | 3.12.1-1ubuntu1.7 | [rabbitmq-server 3.12.1-1ubuntu1.7](https://patchblox.com/security/data/fix/linux/ubuntu-noble-rabbitmq-server-3.12.1-1ubuntu1.7.md) | Oct 19, 2026 |
| Linux | rabbitmq-server Ubuntu 26.04.1 LTS (resolute) | 4.0.5-10ubuntu5.2 | [rabbitmq-server 4.0.5-10ubuntu5.2](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-rabbitmq-server-4.0.5-10ubuntu5.2.md) | Sep 25, 2026 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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