CVE-2026-56817
Received
Received - Intake
XML External Entity Injection in Netty Framework
Vulnerability report for CVE-2026-56817, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-07-21
Last updated on: 2026-07-21
Assigner: GitHub, Inc.
Description
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.
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| netty | netty | From 4.1.0.Final (inc) to 4.1.135.Final (inc) |
| netty | netty | From 4.2.0.Final (inc) to 4.2.15.Final (inc) |
| netty | netty | 4.1.136.Final |
| netty | netty | 4.2.16.Final |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-611 | The product processes an XML document that can contain XML entities with URIs that resolve to documents outside of the intended sphere of control, causing the product to embed incorrect documents into its output. |
