# CVE-2025-67735: Netty has a CRLF Injection vulnerability in io.netty.handler.codec.http.HttpRequestEncoder

Source: https://junglewise.ai/threats/cve-2025-67735-netty-has-a-crlf-injection-vulnerability-in-io-netty-handler  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2025-12-16  
License: CC BY 4.0 with a link back

CVE-2025-67735 · Severity: medium · CVSS 6.5 · Published 2025-12-16

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.

Technologies: [io.netty:netty-codec-http (Maven)](https://junglewise.ai/threats/technologies/io-netty-netty-codec-http), [Netty](https://junglewise.ai/threats/technologies/netty). Vendors: [Maven](https://junglewise.ai/threats/vendors/maven), [Netty](https://junglewise.ai/threats/vendors/netty).

## Quick answers

**Is CVE-2025-67735 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2025-67735 being exploited in the wild.

**How severe is CVE-2025-67735?** Medium severity, with a CVSS score of 6.5, published 16 December 2025.

**Which products and versions are affected?** io.netty:netty-codec-http (Maven) ECOSYSTEM:introduced=4.2.0.Alpha1,fixed=4.2.8.Final.

**Is there a fix for CVE-2025-67735?** Yes. io.netty:netty-codec-http (Maven): upgrade to 4.2.8.Final or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**Am I affected by CVE-2025-67735?** Check whether you run io.netty:netty-codec-http (Maven) or Netty at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- io.netty:netty-codec-http (Maven): upgrade to 4.2.8.Final or later

  ```sh
  # set io.netty:netty-codec-http to 4.2.8.Final in your pom.xml or build.gradle
  ```


## Affected products

- io.netty:netty-codec-http (Maven) ECOSYSTEM:introduced=4.2.0.Alpha1,fixed=4.2.8.Final
- Netty

## Identifiers

- CVE-2025-67735
- GHSA-84h7-rjj3-6jx4

## Related threats

- [Netty HTTP/1 decoder request smuggling](https://junglewise.ai/threats/cve-2026-93562-a-flaw-was-found-in-netty-s-http-1-decoder-incomplete-validation)
- [Netty HTTP/1 to HTTP/2 conversion authority mismatch](https://junglewise.ai/threats/cve-2026-93569-netty-http-1-to-http-2-conversion-authority-mismatch)
- [Netty HTTP request smuggling via control characters in chunk size](https://junglewise.ai/threats/cve-2026-93566-netty-http-request-smuggling-via-control-characters-in-chunk-size)
- [Netty RtspDecoder method-token smuggling in RTSP parsing](https://junglewise.ai/threats/cve-2026-93565-netty-rtspdecoder-method-token-smuggling-in-rtsp-parsing)
- [Netty reference-count leak in HAProxy PROXY-v2 decoder](https://junglewise.ai/threats/cve-2026-93564-netty-reference-count-leak-in-haproxy-proxy-v2-decoder)