CVE-2026-77406: RabbitMQ amqp091-go resource exhaustion via signed-to-unsigned integer casting in QoS

CVE-2026-77406 · Severity: high · CVSS 4 · Published 2026-09-16

The RabbitMQ Go AMQP client library contains a flaw in its Quality of Service (QoS) configuration that converts negative parameter values to very large unsigned integers. When a developer passes a negative number (commonly used to mean "no limit") for message prefetch settings, the client silently converts it to maximum values instead, causing the message broker to flood the application with unlimited messages. This can rapidly exhaust memory and crash the application.

Technologies: github.com/rabbitmq/amqp091-go (Go), RabbitMQ Amqp091-Go. Vendors: Go, RabbitMQ.

Quick answers

Is CVE-2026-77406 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-77406 being exploited in the wild.
How severe is CVE-2026-77406?
High severity, with a CVSS score of 4, published 16 September 2026.
Which products and versions are affected?
github.com/rabbitmq/amqp091-go (Go) < 1.13.0, SEMVER:introduced=0,fixed=1.13.0; RabbitMQ Amqp091-Go affected versions prior to patch.
Is there a fix for CVE-2026-77406?
Yes. github.com/rabbitmq/amqp091-go (Go): upgrade to 1.13.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-77406 attacked?
It is attacked with local access, in a software library.
Am I affected by CVE-2026-77406?
Check whether you run github.com/rabbitmq/amqp091-go (Go) or RabbitMQ Amqp091-Go at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • github.com/rabbitmq/amqp091-go (Go): upgrade to 1.13.0 or later
    go get github.com/rabbitmq/amqp091-go@v1.13.0

Technical details

The vulnerability exists in the AMQP client's Qos method, which accepts signed integers (int) for prefetchCount and prefetchSize but directly casts them to unsigned integers (uint16 and uint32) without validation. Go's implicit signed-to-unsigned conversion via two's complement wraps negative values to maximum range limits (e.g., -1 becomes 65535 or 4294967295). An attacker or misconfigured application that passes negative integers to these parameters triggers an unintended maximum-capacity QoS request, causing the broker to send an unlimited stream of messages to the consumer. The attack vector is application-level configuration manipulation; no authentication bypass or network exploitation is required. The resulting message flood causes rapid memory exhaustion and denial of service.

Affected products

  • RabbitMQ amqp091-go affected versions prior to patch

Identifiers

  • CVE-2026-77406
  • GHSA-rm6m-hrcw-jw33
  • GO-2026-6502

Timeline

  • 2026-09-17: disclosed

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