CVE-2026-42584 HIGH

CVE-2026-42584: Netty: HttpClientCodec response desynchronization

Vendor Netty
Product netty
Weakness CWE-444
Published May 13, 2026
Last update June 30, 2026

CVSS base score

7.3/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality Low
Integrity Low

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

What the vulnerability does

01Description

Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, HttpClientCodec pairs each inbound response with an outbound request by queue.poll() once per response, including for 1xx. If the client pipelines GET then HEAD and the server sends 103, then 200 with GET body, then 200 for HEAD, the queue pairs HEAD with the first 200. The HEAD rule then skips reading that message’s body, so the GET entity bytes stay on the stream and the following 200 is parsed from the wrong offset. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.

Key dates

02Disclosure timeline

May 13, 2026 CVE published
June 30, 2026 Record updated