CVE-2026-77412: RabbitMQ amqp091-go: Denial of Service via Malicious Field Length in AMQP Client

Summary A vulnerability in the readField function allows a malicious or compromised AMQP server to trigger an unhandled runtime panic in the client application, leading to an immediate crash of the entire process.

Details When parsing incoming AMQP frames, the readField function processes byte-array fields (type tag 'x') by reading a 32-bit big-endian integer to determine the length of the data payload.

// read.go:253-263
case 'x':
var len int32
if err = binary.Read(r, binary.BigEndian, &len); err != nil {
return nil, err
}
value := make([]byte, len)  // PANICS if len < 0

If a server transmits a length value of 0xFFFFFFFF, it is interpreted by the client as a signed 32-bit integer with a value of -1. Passing a negative integer to Go’s built-in make() function for slice allocation triggers an unrecoverable runtime panic (panic: len out of range).

Because the reader goroutine handles network I/O without an explicit recover() wrapper, this panic propagates up to the runtime root, abruptly terminating the host application.

Attack Vector / Exploitation Scenario An attacker capable of spoofing, compromising, or controlling an AMQP broker can exploit this flaw during two primary phases:

1. Connection Establishment: Sending a malicious connection.start handshake frame containing server-properties with an ‘x’ type field assigned a negative length.
2. Message Delivery: Delivering a message payload where the header table contains a malformed field matching the criteria above.

Impact Availability: High. A single malformed frame can reliably crash the client process, resulting in a persistent Denial of Service (DoS) if the client automatically reconnects and receives the same payload.