Netty up to 4.1.135.Final/4.2.15.Final HAProxy Encoder crlf injection

Summaryinfo

A vulnerability has been found in Netty up to 4.1.135.Final/4.2.15.Final and classified as critical. This vulnerability affects unknown code of the component HAProxy Encoder. The manipulation leads to crlf injection. This vulnerability is listed as CVE-2026-59919. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability was found in Netty up to 4.1.135.Final/4.2.15.Final and classified as critical. This issue affects an unknown part of the component HAProxy Encoder. The manipulation with an unknown input leads to a crlf injection vulnerability. Using CWE to declare the problem leads to CWE-93. The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

Netty is an asynchronous, event-driven network application framework. In versions prior to 4.1.136.Final and 4.2.16.Final, Netty's HAProxy encoder ( HAProxyMessageEncoder ) writes AF_UNIX source and destination socket addresses into the HAProxy V1 text protocol without validating them for CRLF characters, so an attacker who controls an AF_UNIX address can inject  \r\n  sequences and split the single PROXY header into multiple lines. This is possible because the V1 protocol uses CRLF as its line terminator and, unlike IPv4/IPv6 addresses whose format checks implicitly reject CRLF, AF_UNIX addresses are only validated for length (up to 108 bytes), allowing a forged second PROXY header line that spoofs the client source/destination IP to a downstream server or load balancer. The issue is fixed in versions 4.1.136.Final and 4.2.16.Final.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-59919 since 07/07/2026. The exploitation is known to be easy. The attack may be initiated remotely. Neither technical details nor an exploit are publicly available.

Upgrading to version 4.1.136.Final or 4.2.16.Final eliminates this vulnerability.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Name

• Netty

Version

• 4.1.135.Final
• 4.2.15.Final

Website

• Product: https://github.com/netty/netty/

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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