Bug 2477231 (CVE-2026-44248)

Summary:	CVE-2026-44248 netty: io.netty/netty-codec-mqtt: Netty: Denial of Service due to excessive resource consumption from crafted MQTT 5 header
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:	anujha, aschwart, asoldano, aszczucz, ataylor, bbaranow, bmaxwell, boliveir, bstansbe, dbruscin, dhanak, dlofthou, drichtar, drosa, ehugonne, fmariani, gmalinko, ibek, istudens, ivassile, iweiss, janstey, jrokos, jwon, kvanderr, mcarlett, mnovotny, mosmerov, mposolda, msvehla, nwallace, pberan, pdelbell, pesilva, pjindal, pmackay, rmartinc, rstancel, rstepani, sausingh, smaestri, ssilvert, sthorger, tcunning, thjenkin, vdosoudi, vmuzikar, yfang
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
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Doc Text:	A flaw was found in Netty, an asynchronous event-driven network application framework. A remote attacker can exploit this vulnerability by sending a crafted MQTT 5 header with an oversized Properties section. This causes Netty to repeatedly parse and buffer the large Properties section in memory before any message size limits are applied, leading to high CPU and memory consumption. This can result in a Denial of Service (DoS) condition, making the affected system unavailable.	Story Points:	---
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Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-05-13 19:02:44 UTC

Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, the MQTT 5 header Properties section is parsed and buffered before any message size limit is applied. Specifically, in MqttDecoder, the decodeVariableHeader() method is called before the bytesRemainingBeforeVariableHeader > maxBytesInMessage check. The decodeVariableHeader() can call other methods which will call decodeProperties(). Effectively, Netty does not apply any limits to the size of the properties being decoded. Additionally, because MqttDecoder extends ReplayingDecoder, Netty will repeatedly re-parse the enormous Properties sections and buffer the bytes in memory, until the entire thing parses to completion. This can cause high resource usage in both CPU and memory. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.

Comment 2 errata-xmlrpc 2026-07-09 15:30:39 UTC

This issue has been addressed in the following products:

  Red Hat build of Apache Camel 4.18.1.P1 for Spring Boot 3.5.16

Via RHSA-2026:37390 https://access.redhat.com/errata/RHSA-2026:37390

Comment 3 errata-xmlrpc 2026-07-20 11:59:26 UTC

This issue has been addressed in the following products:

  Red Hat Data Grid 8.6.2

Via RHSA-2026:41951 https://access.redhat.com/errata/RHSA-2026:41951