CVE-2026-42578 | THREATINT

Description

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.

PUBLISHED Reserved 2026-04-28 | Published 2026-05-13 | Updated 2026-05-13 | Assigner GitHub_M

LOW: 2.9CVSS: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

Problem types

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

Product status

>= 4.2.0.Alpha1, < 4.2.13.Final

affected

< 4.1.133.Final

affected

References

github.com/.../netty/security/advisories/GHSA-45q3-82m4-75jr exploit

github.com/.../netty/security/advisories/GHSA-45q3-82m4-75jr

cve.org (CVE-2026-42578)

nvd.nist.gov (CVE-2026-42578)

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