CVE-2026-56817

CRITICAL

Netty: XML External Entity (XXE) injection via unconfigured XML factory when DTD and entity processing are enabled

Title source: cna
STIX 2.1

Description

Netty is a network application framework for development of protocol servers and clients. In versions 4.2.0.Final through 4.2.15.Final and 4.1.0.Final through 4.1.135.Final, any caller that can deliver bytes to a Netty channel pipeline containing `XmlDecoder` can send XML with a `DOCTYPE` declaration to an `AsyncXMLInputFactory` instantiated with no security configuration, leaving DTD and entity handling active depending on Aalto XML async parser behavior and creating conditional XML external entity risk. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.

References (5)

Core 5

Scores

CVSS v3 9.8
EPSS 0.0032
EPSS Percentile 24.4%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CISA SSVC

Vulnrichment
Exploitation none
Automatable yes
Technical Impact partial

Details

CWE
CWE-611
Status published
Products (5)
io.netty/netty-codec-xml 4.1.0.Final - 4.1.136.FinalMaven
io.netty/netty-codec-xml 4.2.0.Final - 4.2.16.FinalMaven
netty/netty 4.1.0 - 4.1.136
netty/netty >= 4.1.0.Final, < 4.1.136.Final
netty/netty >= 4.2.0.Final, < 4.2.16.Final
Published Jul 21, 2026
Tracked Since Jul 22, 2026