Vulnerability · Published Sep 3, 2025 · Assigned by GitHub_M
CVE-2025-58056Netty is vulnerable to request smuggling due to incorrect parsing of chunk extensions
Low 2.9
In plain English
A low-severity security flaw in netty from netty. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 54% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | netty | 1:4.1.48-7+deb12u2 | DSA-6160-1 |
| Debian:12 | netty | 1:4.1.48-7+deb12u2 | DEBIAN-CVE-2025-58056 |
| Debian:13 | netty | 1:4.1.48-10+deb13u1 | DSA-6160-1 |
| Debian:13 | netty | 1:4.1.48-10+deb13u1 | DEBIAN-CVE-2025-58056 |
| Debian:14 | netty | 1:4.1.48-13 | DEBIAN-CVE-2025-58056 |
| Maven | io.netty:netty-codec-http | 4.1.125.Final | GHSA-fghv-69vj-qj49 |
| Maven | io.netty:netty-codec-http | 4.2.5.Final | GHSA-fghv-69vj-qj49 |
| Ubuntu:22.04:LTS | netty | 1:4.1.48-4+deb11u2ubuntu0.1 | UBUNTU-CVE-2025-58056 |
| Ubuntu:24.04:LTS | netty | 1:4.1.48-9ubuntu0.1 | UBUNTU-CVE-2025-58056 |
| Ubuntu:25.10 | netty | 1:4.1.48-10ubuntu0.25.10.2 | UBUNTU-CVE-2025-58056 |
Affected products (as reported)
Weakness: CWE-444 · 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
References
- https://github.com/netty/netty/security/advisories/GHSA-fghv-69vj-qj49 x_refsource_CONFIRM
- https://github.com/JLLeitschuh/unCVEed/issues/1 x_refsource_MISC
- https://github.com/netty/netty/issues/15522 x_refsource_MISC
- https://github.com/netty/netty/pull/15611 x_refsource_MISC
- https://github.com/netty/netty/commit/edb55fd8e0a3bcbd85881e423464f585183d1284 x_refsource_MISC
- https://datatracker.ietf.org/doc/html/rfc9112#name-chunked-transfer-coding x_refsource_MISC
- https://w4ke.info/2025/06/18/funky-chunks.html x_refsource_MISC