Staging Environment: Content and features may be unstable or change without notice.
Advisory details: vulnrichment / CVE-2026-50020
Advisory ID vulnrichment/CVE-2026-50020
Aliases
Summary 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.
Status Published
Exploitability 0.5
Weighted Severity 0.0
Risk
Affected and Fixed Packages Package Details
Introduced and Fixed Package Commit Patches Package Commit Patches Details
Weaknesses (1)
CWE-444 Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
System Score Found at
cvssv3.1 5.3
ssvc Track
Reference id Reference type URL
https://github.com/netty/netty/releases/tag/netty-4.1.135.Final
https://github.com/netty/netty/releases/tag/netty-4.2.15.Final
GHSA-hvcg-qmg6-jm4c Other https://github.com/netty/netty/security/advisories/GHSA-hvcg-qmg6-jm4c
No exploits are available.

No EPSS data available for this advisory.

Patch URL
There are no known patches.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Found at None
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:P/A:Y/T:P/P:M/B:A/M:M/D:T/2026-06-12T15:56:10Z/ Found at None

Vector: SSVCv2/E:P/A:Y/T:P/P:M/B:A/M:M/D:T/2026-06-12T15:56:10Z/

Decision: Track

Source URL: https://github.com/cisagov/vulnrichment/blob/develop/2026/50xxx/CVE-2026-50020.json

Source Advisory: vulnrichment/CVE-2026-50020

View SSVC decision tree 
[{'Exploitation': 'poc'},
 {'Automatable': 'yes'},
 {'Technical Impact': 'partial'},
 {'Mission Prevalence': 'minimal'},
 {'Public Well-being Impact': 'material'},
 {'Mission & Well-being': 'medium'}]