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_vhost/2 calls rabbit_data_coercion:atomize_keys/1 (the unsafe variant using binary_to_atom) on the vhost metadata map. The 20 MB management body limit fits ~1M+ short keys. Admin-only. An administrator importing a crafted definitions file can crash the node in a single request: a vhosts entry with ~1M unique metadata keys exhausts the atom table during import. Preconditions include administrator tag. This issue is fixed in versions 3.13.15, 4.0.20, 4.1.11, 4.2.6, and 4.3.0.
https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-ggrw-qm45-hwpv
https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.3.0
https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.2.6
Published: 2026-09-23
Updated: 2026-09-24
Base Score: 4
Vector: CVSS2#AV:N/AC:L/Au:S/C:N/I:N/A:P
Severity: Medium
Base Score: 6.5
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:H
Severity: Medium
Base Score: 6.9
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Severity: Medium
EPSS: 0.00278