Netty: Prior to versions 4.1.135.Final and 4.2.15.Final, before reading the first request-line, HttpObjectDecoder skips every byte for which… (CVE-2026-50020)
Description
Netty versions prior to 4.1.135.Final and 4.2.15.Final contain a vulnerability in HttpObjectDecoder where it skips all ISO control bytes and whitespace before reading the first HTTP request line. This behavior exceeds the HTTP specification's allowance to ignore only empty CRLF lines before the request line, potentially causing request-boundary confusion in pipelined or multiplexed transports. The issue is patched in versions 4.1.135.Final and 4.2.15.Final.
CVSS v3.1
Score 5.3medium
Affected software
pkg:deb/ubuntu/netty?arch=source&distro=esm-infra-legacy/trustypkg:deb/ubuntu/netty?arch=source&distro=esm-apps-legacy/xenialpkg:deb/ubuntu/netty?arch=source&distro=esm-apps/bionicpkg:deb/ubuntu/netty?arch=source&distro=esm-apps/focalpkg:deb/ubuntu/netty?arch=source&distro=esm-apps/jammypkg:deb/ubuntu/netty?arch=source&distro=esm-apps/noblepkg:deb/ubuntu/netty?arch=source&distro=questingpkg:deb/ubuntu/netty?arch=source&distro=stonkingpkg:deb/ubuntu/netty?arch=source&distro=esm-apps/resoluteRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Netty, a network application framework, had a vulnerability (CVE-2026-50020) in versions before 4.1.135.Final and 4.2.15.Final where the HttpObjectDecoder component skipped every byte classified as an ISO control character (0x00–0x1F and 0x7F) and all whitespace before reading the first HTTP request line. According to RFC 9112 §2.2, servers should only ignore empty CRLF lines preceding the request line. The broader skipping of control characters can be exploited to cause request-boundary confusion in pipelined or multiplexed HTTP transports, especially when front-end components treat these bytes differently. The vulnerability is fixed in the specified versions.
Potential Impact
The vulnerability allows an attacker to exploit the excessive skipping of control characters before the HTTP request line, potentially causing confusion in request boundaries in pipelined or multiplexed HTTP transports. This can lead to issues in front-end components that handle these bytes differently, potentially impacting the integrity of HTTP request processing. The CVSS score is 5.3 (medium severity), indicating limited impact on confidentiality and availability but some impact on integrity.
Mitigation Recommendations
A fix is available in Netty versions 4.1.135.Final and 4.2.15.Final. Users should upgrade to these or later versions to remediate the vulnerability. No other mitigation actions are specified or required.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- UBUNTU-CVE-2026-50020
- Osv Schema Version
- 1.7.0
- Ecosystems
- ["Ubuntu:Pro:14.04:LTS","Ubuntu:Pro:16.04:LTS","Ubuntu:Pro:18.04:LTS","Ubuntu:Pro:20.04:LTS","Ubuntu:Pro:22.04:LTS","Ubuntu:Pro:24.04:LTS","Ubuntu:25.10","Ubuntu:26.10","Ubuntu:Pro:26.04:LTS"]
- Cvss Version
- 3.1
Threat ID: 6ad3f6142cdf04f65666415a
Added to database: 10/17/2026, 22:26:28 UTC
Last enriched: 10/18/2026, 01:02:05 UTC
Last updated: 10/18/2026, 01:02:05 UTC
Views: 2
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