Vulnerability · Published Jul 29, 2026 · Assigned by GitHub_M
CVE-2026-59919Netty: HAProxy V1 Protocol CRLF Injection via AF_UNIX Address
Medium 5.5
In plain English
A medium-severity security flaw in netty from netty. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 6% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | netty | no fix listed | DEBIAN-CVE-2026-59919 |
| Debian:13 | netty | no fix listed | DEBIAN-CVE-2026-59919 |
| Debian:14 | netty | no fix listed | DEBIAN-CVE-2026-59919 |
| Maven | io.netty:netty-codec-haproxy | 4.2.16.Final | GHSA-wh89-7897-x99h |
| Maven | io.netty:netty-codec-haproxy | 4.1.136.Final | GHSA-wh89-7897-x99h |
| Ubuntu:26.10 | netty | no fix listed | UBUNTU-CVE-2026-59919 |
Affected products (as reported)
Weakness: CWE-93 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
References
- https://github.com/netty/netty/security/advisories/GHSA-wh89-7897-x99h x_refsource_CONFIRM