Bug 2535493 (CVE-2026-77406)

Summary:	CVE-2026-77406 github.com/rabbitmq/amqp091-go: RabbitMQ amqp091-go: Denial of Service via signed-to-unsigned integer casting
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	aazores, cmah, dhanak, doconnor, drosa, dsimansk, eaguilar, ebaron, eglynn, gparvin, jbalunas, jjoyce, jmatsuok, jpretori, jschluet, jtolenti, kingland, lhh, mburns, mgarciac, mnovotny, pjindal, rhaigner, sausingh, tsze
Target Milestone:	---	Keywords:	Security
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Hardware:	All
OS:	Linux
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Doc Text:	A flaw was found in RabbitMQ amqp091-go. The `Channel.Qos` function in `channel.go` incorrectly handles negative integer values for `prefetchCount` and `prefetchSize`, casting them to large unsigned integers. This allows an application that processes untrusted Quality of Service (QoS) configuration to request extremely high message prefetch limits. Consequently, a message broker can deliver a large volume of queued messages, leading to client memory exhaustion and a Denial of Service (DoS) condition.	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-09-16 14:53:13 UTC

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.