RabbitMQ amqp091-go: Resource Exhaustion (OOM) via Unbounded Body Buffer Allocation

Summary A flaw in the recvContent function allows a malicious AMQP server to trigger an Out-of-Memory (OOM) error, forcing the host operating system or container runtime to immediately terminate the client process.

Vulnerability Details When receiving message content payloads, the client processes the expected size from the content header framework. The recvContent function attempts to optimize performance by pre-allocating memory for the message body based on the ch.header.Size field, which is a 64-bit unsigned integer (uint64).

// channel.go:495-496
if cap(ch.body) == 0 {
    ch.body = make([]byte, 0, ch.header.Size)  // unbounded
}

The underlying library fails to validate or cap this requested size against any upper boundary—such as the maximum frame size negotiated during connection establishment (FrameMax). If a server specifies an extreme body size (e.g., 2^62 bytes), the Go runtime attempts to allocate an exabyte-scale slice capacity. This immediately exhausts available system memory, causing the operating system's OOM killer to terminate the application.

Attack Vector / Exploitation Scenario

• Message Delivery Phase: A malicious or compromised AMQP broker sends a standard basic.deliver frame containing a content header with an intentionally inflated body-size variable.
• Authentication Requirement: No special privileges or authentication bypasses are required; the crash occurs seamlessly during normal message consumption.

Impact

• Availability: High. Exploded memory consumption results in an instant process termination, destroying application state and availability for all threads sharing the environment.