CVE-2026-42584

Netty: HttpClientCodec response desynchronization

Published May 13, 2026 CVSS 3.1 · 7.3 High EPSS < 1% KEV · Not listed
Description
Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, HttpClientCodec pairs each inbound response with an outbound request by queue.poll() once per response, including for 1xx. If the client pipelines GET then HEAD and the server sends 103, then 200 with GET body, then 200 for HEAD, the queue pairs HEAD with the first 200. The HEAD rule then skips reading that message’s body, so the GET entity bytes stay on the stream and the following 200 is parsed from the wrong offset. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-57rv-r2g8-2cj3 Netty has HttpClientCodec response desynchronization
Ubuntu USN Ubuntu USN USN-8401-1 Netty vulnerabilities
History
Type Values Removed Values Added
CPEs cpe:2.3:a:netty:netty:*:*:*:*:*:*:*:*
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Io.netty
Io.netty netty-codec-http
Netty
Netty netty
Vendors & Products Io.netty
Io.netty netty-codec-http
Netty
Netty netty
Type Values Removed Values Added
Description Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, HttpClientCodec pairs each inbound response with an outbound request by queue.poll() once per response, including for 1xx. If the client pipelines GET then HEAD and the server sends 103, then 200 with GET body, then 200 for HEAD, the queue pairs HEAD with the first 200. The HEAD rule then skips reading that message’s body, so the GET entity bytes stay on the stream and the following 200 is parsed from the wrong offset. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.
Title Netty: HttpClientCodec response desynchronization
Weaknesses CWE-444
References
Metrics cvssV3_1

{'score': 7.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Sep 18, 2026, 12:04 PM
Reserved
Apr 28, 2026, 5:26 PM
Status
Modified
Published
May 13, 2026, 7:17 PM
Modified
Oct 26, 2026, 5:10 PM
Severity
Important
Public date
May 13, 2026, 6:10 PM