CVE-2026-42578 PUBLISHED

Netty: HTTP Header Injection via HttpProxyHandler Disabled Validation

Assigner: GitHub_M
Reserved: 28.04.2026 Published: 13.05.2026 Updated: 13.05.2026

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.

Metrics

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
CVSS Score: 2.9

Product Status

Vendor netty
Product netty
Versions
  • Version >= 4.2.0.Alpha1, < 4.2.13.Final is affected
  • Version < 4.1.133.Final is affected

References

Problem Types

  • CWE-113: Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting') CWE