Vulnerability in Netty

CVE-2025-67735

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.

Vulnerability class: CRLF Injection

Published · last modified .

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.003 (22.6th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 23rd percentile — 22.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2025-67735: held from 0.003 to 0.003.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: -0.000

Affected products

  • Netty — versions >= 4.2.0.Alpha1, < 4.2.8.Final, < 4.1.129.Final

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2025-67735?
CVE-2025-67735 is a medium-severity vulnerability in Netty, classified under CRLF Injection. CVSS score: 6.5/10. Published 2025-12-16.
How severe is CVE-2025-67735?
Medium severity. CVSS v3 base score is 6.5 out of 10.