CVE-2026-42578

HIGH 7.5

Netty: HTTP Header Injection via HttpProxyHandler Disabled Validation

CVSS Score

7.5

EPSS Score

1.1%

EPSS Percentile

63th

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.

CWE	CWE-113
Vendor	netty
Product	netty
Published	May 13, 2026
Last Updated	Sep 18, 2026

Stay Ahead of the Next One

Get instant alerts for netty netty

Be the first to know when new high vulnerabilities affecting netty netty are published — delivered to Slack, Telegram or Discord.

Get Free Alerts → Free · No credit card · 60 sec setup

Affected Versions

netty / netty

>= 4.2.0.Alpha1, < 4.2.13.Final < 4.1.133.Final

References

NVD ↗ CVE.org ↗ EPSS Data ↗