Netty XML: Injection / Risky Sink — unconfigured XML factory with active DTD and entity handling

緊急 9.8CVE-2026-56817 · GHSA-4qhr-g3c6-fcfx · 21/07/2026 公開 · 30/07/2026 更新

要点

CVE-2026-56817 は io.netty:netty-codec-xml, netty (netty) に影響する深刻度「緊急」 (CVSS 9.8) の脆弱性です。
今後30日間に悪用される確率（EPSS）：0.69%（全脆弱性の 53.0% より高い）。
対処：4.1.136.Final, 4.2.16.Final, 4.1.136, 4.2.16 以降に更新してください。

パッケージ	影響を受けるバージョン	修正済みバージョン
io.netty:netty-codec-xml Maven	`≥ 4.1.0.Final, < 4.1.136.Final≥ 4.2.0.Final, < 4.2.16.Final`	`4.1.136.Final4.2.16.Final`
netty netty	`≥ 4.1.0, < 4.1.136≥ 4.2.0, < 4.2.16`	`4.1.1364.2.16`

概要

Any caller that can deliver bytes to a Netty channel pipeline containing XmlDecoder can send XML with a DOCTYPE declaration to a parser instantiated with no security configuration — but whether external entities are actually resolved depends on Aalto XML's async parser behavior, making this a confirmed misconfiguration with conditional exploitability.

NVD の説明

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.