CRLF Injection Affecting netty package, versions <1:4.1.48-9ubuntu0.2+esm1


Severity

Recommended
medium

Based on Ubuntu security rating.

Threat Intelligence

EPSS
0.33% (26th percentile)

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  • Snyk IDSNYK-UBUNTU2404-NETTY-14460035
  • published27 Aug 2026
  • disclosed16 Dec 2025

Introduced: 16 Dec 2025

CVE-2025-67735  (opens in a new tab)
CWE-93  (opens in a new tab)

How to fix?

Upgrade Ubuntu:24.04 netty to version 1:4.1.48-9ubuntu0.2+esm1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream netty package and not the netty package as distributed by Ubuntu. See How to fix? for Ubuntu:24.04 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1