RabbitMQ EUVD-2026-87237

Requires: (1) the RabbitMQ Management plugin enabled (it exposes the vulnerable /api/global-parameters/:name HTTP endpoint); (2) an authenticated account carrying the 'policymaker' user tag - not the weaker management tag, but below administrator; and (3) the ability to send a very high volume (~1,000,000) of requests each with a unique :name value to sustain atom-table growth to the exhaustion point. The single-request AT:P attack requirement and the privileged-role gating are the primary limiting factors; the endpoint is not reachable by unauthenticated or low-privilege users, and default deployments without the Management plugin are not exposed. Applies to RabbitMQ 4.0.0 up to (but not including) 4.0.22, 4.1.14, 4.2.7, and 4.3.1.

This is a genuine but modest-priority denial-of-service issue, not a high-urgency threat. The NVD CVSS 4.0 vector (AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:N/VA:H, score 5.9) correctly captures a pure availability impact with no confidentiality or integrity effect. Two signals temper the risk: PR:H/PR:L means the attacker must already hold a privileged RabbitMQ role, and AT:P reflects that a single request is harmless - the crash requires roughly 1,000,000 requests with unique names to exhaust the atom table, so this is a sustained-volume attack, not a one-shot. No EPSS score, no CISA KEV listing, and no public exploit are present in the provided data, indicating no evidence of active or automated exploitation. One data conflict to flag: NVD assigns PR:H, but the description explicitly states the endpoint requires only the 'policymaker' tag, which sits BELOW administrator - so PR:L is arguably more accurate, and the vendor CVSS may overstate the privilege barrier. Overall this is a high-CVSS-but-bounded-real-risk item: a legitimately privileged insider (or a compromised policymaker credential) can crash a node, affecting all tenants on it, but external unauthenticated attackers cannot reach it.

An authenticated user holding the RabbitMQ policymaker tag (or an attacker who has stolen such credentials) scripts roughly a million HTTP requests to /api/global-parameters/<unique-name>, each with a distinct name. Because resource_exists/2 and the PUT/DELETE handlers coerce the URL :name segment to an atom via the unsafe binary_to_atom/2, every unique name permanently consumes an atom-table slot until the BEAM VM hits its atom limit and the node crashes, taking down all vhosts and tenants on it. No public exploit code is identified, but the technique is trivial to reproduce with a simple loop.