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list_to_atom on auth_mechanism URI tokens in amqp_client

Moderate
ansd published GHSA-85jr-6rr2-j73r Jul 9, 2026

Software

rabbitmq-server

Affected versions

>= 3.13.0, < 3.13.15
>= 4.0.0, < 4.0.20
>= 4.1.0, < 4.1.11
>= 4.2.0, < 4.2.6

Patched versions

3.13.15
4.0.20
4.1.11
4.2.6

Description

Origin

This vulnerability was identified by Team RabbitMQ and/or other teams at Broadcom, not via a responsible disclosure from an external researcher.

Description

mechanisms/1 calls [list_to_atom(T) || T <- string:tokens(Mech, ":")] on every auth_mechanism query value. A single ~9 MB PUT fits roughly 1M colon-separated tokens, and each becomes a permanent atom, crashing the node in one to three requests.

Preconditions

The Shovel or Federation plugin must be in use. Setting auth_mechanism requires the policymaker tag.

CVSS

CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N (5.9, Moderate). Fixed in 3.13.15, 4.0.20, 4.1.11, 4.2.6, 4.3.0.

Severity

Moderate

CVE ID

No known CVE

Weaknesses

Uncontrolled Resource Consumption

The product does not properly control the allocation and maintenance of a limited resource. Learn more on MITRE.