CVE-2026-59919Public exploit

Client IP spoofing via AF_UNIX CRLF injection

Published Jul 29, 2026 · Updated Jul 29, 2026

CRLF injection in Netty before 4.1.136.Final and 4.2.0.Final through 4.2.15.Final allows attackers to spoof client IPs via AF_UNIX addresses. HAProxyMessageEncoder.encodeV1 writes source and destination addresses directly into a CRLF-delimited V1 header, while checkAddress enforces only AF_UNIX length. Exploitation requires an application to encode attacker-controlled AF_UNIX addresses and forward the header; an injected PROXY line can misstate the client identity downstream.

CVSS severity5.5
Medium
EPSS probability0.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

CRLF injection in Netty before 4.1.136.Final and 4.2.0.Final through 4.2.15.Final allows attackers to spoof client IPs via AF_UNIX addresses. HAProxyMessageEncoder.encodeV1 writes source and destination addresses directly into a CRLF-delimited V1 header, while checkAddress enforces only AF_UNIX length. Exploitation requires an application to encode attacker-controlled AF_UNIX addresses and forward the header; an injected PROXY line can misstate the client identity downstream.

The record

CVE
CVE-2026-59919
Published
Jul 29, 2026
Updated
Jul 29, 2026
Vendor
The Netty Project
Product
Netty
Classifications
CWE-93, T1036
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 29, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 29, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 4.1.136.Final
  2. Affected versionversion=>= 4.2.0.Final, < 4.2.16.Final

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Netty Project · Nettyversion=< 4.1.136.Final; version=>= 4.2.0.Final, < 4.2.16.Final

Published CVSS scores

5.5GitHub, Inc.CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-93Improper Neutralization of CRLF Sequences ('CRLF Injection')
T1036Masquerading

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo