CVE-2026-59919: 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

mediumCVSS 5.5CVE-2026-59919

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.

Details

Source: NVD Recent CVEs (US · database · site)
Severity: medium — CVSS 5.5
Published: 2026-07-29
Last updated: 2026-07-30
Exploitation: Not in CISA KEV at last sync

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-59919

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-599190.11% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 1% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-59919	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

medium[NEW] [medium] Netty: Multiple vulnerabilitiescert-bund
mediumGHSA-wh89-7897-x99h: Netty: HAProxy V1 Protocol CRLF Injection via AF_UNIX Addressghsa

Recent advisories for Netty is an

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

highGHSA-93wv-jw9v-4972: Netty: HTTP/2 decompression leaks ByteBuf reference count when the decompressor channel i…ghsa · 2026-07-31
medium[NEW] [medium] Netty: Multiple vulnerabilitiescert-bund · 2026-07-30
high[NEW] [high] Netty: Multiple vulnerabilitiescert-bund · 2026-07-30
high[UPDATE] [high] Netty: Multiple vulnerabilitiescert-bund · 2026-07-30
unknownCVE-2026-59898: Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.13…nvd · 2026-07-29
mediumCVE-2026-59920: Netty is an asynchronous, event-driven network application framework. In versions prior to 4.1…nvd · 2026-07-29