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
EPSS: 0.003 (22.0th percentile) — read the EPSS interpretation.
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.
Affected products
- Netty — versions >= 4.2.0.Alpha1, < 4.2.8.Final, < 4.1.129.Final
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Exploit, Vendor Advisory)
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.