PT-2026-48904 · Netty · Netty

Published 2026-06-12 · Updated 2026-06-12 · CVE-2026-50020

Mitre

CVSS v3.1

5.3

Medium

Base vector

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

Netty is a network application framework for development of protocol servers and clients. Prior to versions 4.1.135.Final and 4.2.15.Final, before reading the first request-line, HttpObjectDecoder skips every byte for which Character.isISOControl(b) is true (0x00–0x1F and 0x7F) as well as all whitespace. RFC 9112 §2.2 only asks servers to ignore empty CRLF lines preceding the request-line — a carefully scoped robustness allowance intended to handle HTTP/1.0 POST workarounds. Silently absorbing NUL bytes, SOH, STX, and other non-CRLF control characters goes significantly beyond this, and can be exploited for request-boundary confusion in pipelined or multiplexed transports where a front-end component treats those bytes differently. Versions 4.1.135.Final and 4.2.15.Final patch the issue.

Fix

HTTP Request/Response Smuggling

Weakness Enumeration

CWE-444

Related Identifiers

CVE-2026-50020

Affected Products

Netty

References · 4

• https://nvd.nist.gov/vuln/detail/CVE-2026-50020 · Security Note
• https://github.com/netty/netty/releases/tag/netty-4.2.15.Final · Note
• https://github.com/netty/netty/releases/tag/netty-4.1.135.Final · Note
• https://github.com/netty/netty/security/advisories/GHSA-hvcg-qmg6-jm4c · Note