The amqp091-go client fails to enforce the 4 KB pre‑negotiation frame size limit, allowing an attacker to send a frame header declaring a large payload before the connection has been fully negotiated. This causes the client to allocate memory controlled by the attacker, leading to significant memory pressure, potential out‑of‑memory termination, or the loss of the client process prior to authentication. The flaw is primarily a denial‑of‑service vector that undermines availability of applications using the library.

The vulnerability affects the RabbitMQ amqp091-go Go AMQP 0.9.1 client library in each release from 1.13.0 up to, but not including, 1.14.0. Consumers of these versions that accept connections from untrusted peers are at risk; the problem is resolved in the public 1.14.0 release and subsequent versions.

The CVSS score of 6.3 indicates moderate severity, and the vulnerability can be triggered over any publicly reachable AMQP port because the exploit requires only the ability to transmit a specially crafted frame before authentication. While EPSS data is not available and the issue is not listed in CISA KEV, the attack path is straightforward: a malicious or compromised AMQP peer can send a small-header, large-payload frame that forces the client to allocate attacker‑controlled memory. The resulting memory exhaustion can terminate the client and potentially cascade to affected services, making timely mitigation advisable.