The vulnerability arises from how RabbitMQ processes Shovel parameters. Attackers can submit crafted runtime parameters through the Management HTTP API, causing the server to create Erlang atoms from those values before validating them or limiting their number. Each parameter becomes a permanent atom. By submitting many unique parameters, an attacker can fill the node‑wide atom table, exhausting the resource and leading to a broker‑wide denial of service. Even after the broker restarts, the malicious parameters are re‑parsed, so the issue can persist without a continuous connection.

Affected are RabbitMQ Server releases 4.2.0 through 4.2.9 and 4.3.3. An attacker needs access to the Management REST API, valid credentials that grant both the management and policymaker roles, permission to set Shovel runtime parameters on a virtual host, and the rabbitmq_shovel and rabbitmq_shovel_management plugins must be enabled. Versions 4.2.9 and 4.3.3 contain the fix, so any installation of these releases or later is not vulnerable.

The CVSS score of 5.9 indicates moderate severity; the EPSS score is not available and the vulnerability is not listed in CISA's KEV catalog. Exploitability requires network connectivity to the Management API and specific administrative permissions, which limits the threat to environments where such access is granted. However, the impact can be significant, causing a full broker outage, and the deficiency can resurface after a restart if the malicious parameters remain stored.