---
id: CVE-2025-67735
title: 'Netty is an asynchronous, event-driven network application framework'
summary: >-
  Netty is an asynchronous, event-driven network application framework. In
  versions prior to 4.1.129.Final and 4.2.8.Final, the
  `io.netty.handler.codec.http.HttpRequestEncoder` has a CRLF injection with the
  request URI when constructing a …
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N'
cwe:
  - CWE-93
vendor: netty
product: netty
affected:
  - netty < 4.1.129
  - 'netty >= 4.2.0, < 4.2.8'
patched:
  - netty 4.2.8
published: '2025-12-16'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T13:10:00.187'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-67735'
references:
  - url: 'https://github.com/netty/netty/security/advisories/GHSA-84h7-rjj3-6jx4'
    label: security-advisories@github.com
tags:
  - nvd
epss: 0.0032
epssPercentile: 0.2324
ingestedAt: '2026-10-14T13:30:58.435Z'
---

## Overview

Netty is an asynchronous, event-driven network application framework. In versions prior to 4.1.129.Final and 4.2.8.Final, the `io.netty.handler.codec.http.HttpRequestEncoder` has a CRLF injection with the request URI when constructing a request. This leads to request smuggling when `HttpRequestEncoder` is used without proper sanitization of the URI. Any application / framework using `HttpRequestEncoder` can be subject to be abused to perform request smuggling using CRLF injection. Versions 4.1.129.Final and 4.2.8.Final fix the issue.

## Affected

- `netty < 4.1.129`
- `netty >= 4.2.0, < 4.2.8`

## Remediation

Upgrade past the affected range:

- `netty 4.2.8`