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CVE-2026-42578

Netty: HTTP Header Injection via HttpProxyHandler Disabled Validation

CVSS 4.0 2.9 LOWCheck source for fixed versionsKEV status unknown

Original advisory

cve-program · CVE-2026-42578

Published

Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, Netty's HttpProxyHandler constructs HTTP CONNECT requests with header validation explicitly disabled. The newInitialMessage() method creates headers using DefaultHttpHeadersFactory.headersFactory().withValidation(false), then adds user-provided outboundHeaders without any CRLF validation. This allows an attacker who can influence the outbound headers to inject arbitrary HTTP headers into the CONNECT request sent to the proxy server. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.

Read the publisher's advisory

Affected versions, risk and source history

cve-program · CVE-2026-42578

Published

netty

Vendor product

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "vendor": "netty",
                    "product": "netty",
                    "versions": [
                        {
                            "version": ">= 4.2.0.Alpha1, < 4.2.13.Final",
                            "status": "affected"
                        },
                        {
                            "version": "< 4.1.133.Final",
                            "status": "affected"
                        }
                    ]
                }

Original source record · Cite this exact observation · Complete original publisher JSON