Bug 2540099 - CVE-2026-67235 rabbitmq-server: RabbitMQ: Denial of Service via AMQP 0-9-1 body size validation bypass [fedora-all]
Summary: CVE-2026-67235 rabbitmq-server: RabbitMQ: Denial of Service via AMQP 0-9-1 bo...
Keywords:
Status: CLOSED CURRENTRELEASE
Alias: None
Product: Fedora
Classification: Fedora
Component: rabbitmq-server
Version: rawhide
Hardware: Unspecified
OS: Unspecified
medium
medium
Target Milestone: ---
Assignee: Peter Lemenkov
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard: {"flaws": ["40a51b2c-03a2-49f5-9fe7-6...
Depends On:
Blocks: CVE-2026-67235
TreeView+ depends on / blocked
 
Reported: 2026-09-24 14:08 UTC by Jon Weiser
Modified: 2026-10-09 15:45 UTC (History)
2 users (show)

Fixed In Version: rabbitmq-server-4.3.6-1.fc46 rabbitmq-server-4.3.6-1.fc45 rabbitmq-server-4.2.9-2.fc44
Clone Of:
Environment:
Last Closed: 2026-10-09 15:44:18 UTC
Type: ---
Embargoed:


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Description Jon Weiser 2026-09-24 14:08:27 UTC
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

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.

Comment 1 Peter Lemenkov 2026-10-09 13:24:27 UTC
This issue is already fixed upstream in RabbitMQ 4.3.6, which is the version currently built for Fedora rawhide (rabbitmq-server-4.3.6-1.fc46) and Fedora 45 (rabbitmq-server-4.3.6-1.fc45).

Fedora 44 (currently 4.2.9) and Fedora 43 (currently 4.0.9) still need attention; backports/rebases for the still-supported stable branches are being worked on. Leaving this report open to track that remaining work.

Comment 2 Peter Lemenkov 2026-10-09 15:44:18 UTC
This issue is already addressed in the rabbitmq-server builds currently shipped in all maintained Fedora branches:

  * Fedora rawhide: rabbitmq-server-4.3.6-1.fc46
  * Fedora 45:      rabbitmq-server-4.3.6-1.fc45
  * Fedora 44:      rabbitmq-server-4.2.9-2.fc44

No new build is required for these branches, so closing as CURRENTRELEASE.

Fedora 43 (rabbitmq-server-4.0.9) will NOT be updated for this CVE batch: the upstream 4.0.x line ended at 4.0.9 (later 4.0.x fixes are commercial-only, with no public OSS release) and Fedora 43 reaches end of life on 2026-12-09, so a backport to F43 is not worthwhile.


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