CVE-2026-42581

Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, HttpObjectDecoder strips a conflicting Content-Length header when a request carries both Transfer-Encoding: chunked and Content-Length, but only for HTTP/1.1 messages. The guard is absent for HTTP/1.0. An attacker that sends an HTTP/1.0 request with both headers causes Netty to decode the body as chunked while leaving Content-Length intact in the forwarded HttpMessage. Any downstream proxy or handler that trusts Content-Length over Transfer-Encoding will disagree on message boundaries, enabling request smuggling. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.

Affected products

Linuxmint, Netty, Red Os, Ubuntu

Netty

< 4.1.133, 4.2.13

Fix

Available

CVSS 3.1

9.8 CRITICAL

EPSS

0.6% (46th percentile)

Weakness

CWE-444

NVD status

Modified

Published

2026-05-13

No exploit for CVE-2026-42581 has been indexed yet. Our index is built from live traffic and upstream syncs, so this page can only say what it knows — not that no exploit exists.