RabbitMQ amqp091-go is a Go AMQP 0.9.1 client. Prior to 1.13.0, Channel.Qos in channel.go accepts negative prefetchCount and prefetchSize integers and casts them directly to uint16 and uint32 fields in the basic.qos method because validateQos is absent. Values such as -1 therefore wrap to 65535 or 4294967295 instead of being rejected. An application that permits untrusted configuration of these Qos values can unintentionally request extremely large prefetch limits, allowing a broker to deliver enough queued messages to exhaust client memory and disrupt processing. This issue is fixed in version 1.13.0.