CVE-2026-42578 LOW

CVE-2026-42578: Netty: HTTP Header Injection via HttpProxyHandler Disabled Validation

Vendor Netty
Product netty
Weakness CWE-113 · HTTP response splitting
Published May 13, 2026
Last update June 30, 2026
View on NVD All CVEs

CVSS base score

2.9/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality —
Integrity —

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

May 13, 2026 CVE published
June 30, 2026 Record updated