CVE-2025-58056
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.
Does this matter?
Lower severity and a low EPSS score (0.68%). Track it; it rarely justifies an emergency change on its own.
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 4.0
- 2.9 LOWCVSS: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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
- EPSS
- 0.68% probability · 50th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-444
- Affected
- netty/netty
- Source
- security-advisories@github.com
References
- https://datatracker.ietf.org/doc/html/rfc9112#name-chunked-transfer-codingTechnical Description
- https://github.com/JLLeitschuh/unCVEed/issues/1Issue Tracking, Third Party Advisory
- https://github.com/netty/netty/commit/edb55fd8e0a3bcbd85881e423464f585183d1284Patch
- https://github.com/netty/netty/issues/15522Issue Tracking
- https://github.com/netty/netty/pull/15611Issue Tracking, Patch
- https://github.com/netty/netty/security/advisories/GHSA-fghv-69vj-qj49Exploit, Vendor Advisory
- https://w4ke.info/2025/06/18/funky-chunks.htmlBroken Link
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.