Netty is an asynchronous event-driven network application framework for development of maintainable high performance protocol servers and clients. In versions 4.1.124.Final, and 4.2.0.Alpha3 through 4.2.4.Final, Netty incorrectly accepts standalone newline characters (LF) as a chunk-size line terminator, regardless of a preceding carriage return (CR), instead of requiring CRLF per HTTP/1.1 standards. When combined with reverse proxies that parse LF differently (treating it as part of the chunk extension), attackers can craft requests that the proxy sees as one request but Netty processes as two, enabling request smuggling attacks. This is fixed in versions 4.1.125.Final and 4.2.5.Final.
Fix
Patch, vendor advisory and mitigation references on NVD 3
- https://github.com/netty/netty/commit/edb55fd8e0a3bcbd85881e423464f585183d1284 Patch
- https://github.com/netty/netty/pull/15611 Issue Tracking, Patch
- https://github.com/netty/netty/security/advisories/GHSA-fghv-69vj-qj49 Exploit, Vendor Advisory
Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.
Change history 1
- First seenCVSS 2.9 · nettyNVD modified 2026-10-19 17:10
Affected (CPE criteria) 1
cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*
References 7
- https://datatracker.ietf.org/doc/html/rfc9112#name-chunked-transfer-coding Technical Description
- https://github.com/JLLeitschuh/unCVEed/issues/1 Issue Tracking, Third Party Advisory
- https://github.com/netty/netty/commit/edb55fd8e0a3bcbd85881e423464f585183d1284 Patch
- https://github.com/netty/netty/issues/15522 Issue Tracking
- https://github.com/netty/netty/pull/15611 Issue Tracking, Patch
- https://github.com/netty/netty/security/advisories/GHSA-fghv-69vj-qj49 Exploit, Vendor Advisory
- https://w4ke.info/2025/06/18/funky-chunks.html Broken Link