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OpenAdvisories
Medium · 6.0 CVE-2026-67219 EUVD-2026-85654

RabbitMQ: Consistent-hash exchange unbounded weight

Published Sep 23, 2026 · Updated Sep 24, 2026 · Assigned by GitHub_M

Description

RabbitMQ is a messaging and streaming broker. Prior to versions 3.13.15, 4.0.20, 4.1.11, 4.2.6, and 4.3.0, add_binding/3 parses the routing key as an integer weight N and computes ring positions with lists:seq(NextN0, NextN0 + N - 1). validate_binding/2 only checks N >= 1 , no upper bound. The resulting list is stored in the exchange's Khepri record, replicated cluster-wide, and reloaded on restart. A user with write permission on a consistent-hash exchange and read on a queue can create a binding whose routing key (the hash-ring weight) is an arbitrarily large integer. The broker allocates a list of that many integers via lists:seq/2 and persists it to Khepri across all cluster nodes , a single binding with weight 100000000 allocates ~800 MB on every node and survives restarts. Preconditions include rabbitmq_consistent_hash_exchange plugin enabled write permission on a consistent-hash exchange + read on a queue (standard binding perms). This issue is fixed in versions 3.13.15, 4.0.20, 4.1.11, 4.2.6, and 4.3.0.

Affected products

VendorProductAffectedFixed
rabbitmq rabbitmq-server >= 3.13.0, < 3.13.15, >= 4.0.0, < 4.0.20, >= 4.1.0, < 4.1.11, >= 4.2.0, < 4.2.6 —

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Debian 14 rabbitmq-server 4.3.0-2 —
Debian 13 rabbitmq-server No fix yet —
Debian 12 rabbitmq-server No fix yet —
ReleasePackageFixed inAdvisory
Ubuntu 26.04 LTS rabbitmq-server No fix yet —
Ubuntu 24.04 LTS rabbitmq-server No fix yet —
Ubuntu 22.04 LTS rabbitmq-server No fix yet —
Show 3 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Ubuntu Pro 20.04 LTS rabbitmq-server No fix yet —
Ubuntu Pro 18.04 LTS rabbitmq-server No fix yet —
Ubuntu Pro 16.04 LTS rabbitmq-server No fix yet —
ReleasePackageFixed inAdvisory
Red Hat Hardened Images 1 rabbitmq-server4.3 4.3.6-1.hum1 RHSA-2026:67552

Azure Linux

ReleasePackageFixed inAdvisory
Azure Linux 3 rabbitmq-server 3.13.7-10 —

Advisories 2

References