# CVE-2026-77406: RabbitMQ amqp091-go: Consumer Message Flooding via Signed-to-Unsigned Integer Casting in Qos Configuration

CVE-2026-77406 is fixed in golang-github-rabbitmq-amqp091-go on 1 platform by DEBIAN-CVE-2026-77406 (version 1.14.0-1), released September 18, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-77406
- Priority: High
- CVSS: n/a (Important)
- EPSS: 0.0052
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 16, 2026
- Weakness: Signed to Unsigned Conversion Error
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-77406

## Description

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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | golang-github-rabbitmq-amqp091-go Debian 14 | 1.14.0-1 | [DEBIAN-CVE-2026-77406](https://patchblox.com/security/data/fix/linux/debian-cve-2026-77406.md) | Sep 18, 2026 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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