CVE-2026-67222: Rabbitmq Rabbitmq-Server

Medium severity, CVSS 5.9. EPSS: 0.3% chance of exploitation in the next 30 days.

RabbitMQ is a messaging and streaming broker. From 3.13.0 until 3.13.15, 4.0.20, 4.1.11, and 4.2.6, mechanisms/1 applied list_to_atom/1 to every colon-delimited token in an attacker-controlled auth_mechanism value, permanently consuming Erlang VM atoms and allowing the node to be crashed with a large request. Exploitation requires the Shovel or Federation plugin to be in use, and setting auth_mechanism requires the policymaker tag. This issue is fixed in versions 3.13.15, 4.0.20, 4.1.11, and 4.2.6.

Affected products

• Rabbitmq Rabbitmq-Server: from 3.13.0, before 3.13.15 (fixed in 3.13.15); from 4.0.0, before 4.0.20 (fixed in 4.0.20); from 4.1.0, before 4.1.11 (fixed in 4.1.11); from 4.2.0, before 4.2.6 (fixed in 4.2.6)

Published 2026-09-25. Last modified 2026-09-28.