Description
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.
CVSS breakdown
CVSS 4.0
Attack Vector
Network
Attack Complexity
Low
Attack Requirements
Present
Privileges Required
None
User Interaction
None
Confidentiality (Vulnerable System)
None
Integrity (Vulnerable System)
Low
Availability (Vulnerable System)
None
Confidentiality (Subsequent System)
None
Integrity (Subsequent System)
None
Availability (Subsequent System)
None
E
Physical
CVSS 3.1
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None
Affected products
- netty / netty>= 4.2.0.Alpha3, < 4.2.5.Final – >= 4.2.0.Alpha3, < 4.2.5.Final
- netty / netty<= 4.1.124.Final, < 4.1.125.Final – <= 4.1.124.Final, < 4.1.125.Final
- netty / netty4.1.125
References
- VENDOR_ADVISORYhttps://github.com/netty/netty/security/advisories/GHSA-fghv-69vj-qj49
- MISChttps://github.com/JLLeitschuh/unCVEed/issues/1
- MISChttps://github.com/netty/netty/issues/15522
- PATCHhttps://github.com/netty/netty/pull/15611
- PATCHhttps://github.com/netty/netty/commit/edb55fd8e0a3bcbd85881e423464f585183d1284
- MISChttps://datatracker.ietf.org/doc/html/rfc9112#name-chunked-transfer-coding
- MISChttps://w4ke.info/2025/06/18/funky-chunks.html
Updated 22m ago · 8 sources