CVE-2026-50020
Description
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.
How to fix CVE-2026-50020
No fixed version has been published yet. Mitigate by removing the affected package or applying upstream guidance from the references below.
- —no fix listed
Is CVE-2026-50020 being exploited?
No exploitation signal available. Neither CISA KEV nor a current EPSS score has been published for CVE-2026-50020.
Affected packages (1)
- from 0
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| nvd | CVSS 3.1 | MEDIUM5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N |