Reference page — cumulative record through Wednesday, August 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.
Netty: HttpClientCodec response desynchronization
AV AC PR UI S C I A CVSS EPSS %ile KEV
N L N N U N H H 9.1 .0078 53.1 —
AFFECTED
Product Versions Fixed
netty >= 4.2.0.Alpha1, < 4.2.13.Final – —
netty-codec-http >= 4.2.0.Alpha1, < 4.2.13.Final – —
TIMELINE
Apr 28 Reserved by GitHub_M
May 13 Published (CNA: GitHub_M)
Aug 13 EXPLOIT PUBLISHED — CVE-2026-42584 (netty). Public exploit reference added.
Aug 13 RESCORED — CVE-2026-42584 (netty). CVSS 7.3 → 9.1 (NVD).
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.
Lifecycle
Complete event history — 4 events, chronological
| Date | Event | Detail |
|---|
| April 28, 2026 | Reserved | Reserved by GitHub_M |
| May 13, 2026 | Published | Published (CNA: GitHub_M) |
| August 13, 2026 | EXPLOIT PUBLISHED | EXPLOIT PUBLISHED — CVE-2026-42584 (netty). Public exploit reference added. |
| August 13, 2026 | RESCORED | RESCORED — CVE-2026-42584 (netty). CVSS 7.3 → 9.1 (NVD). |
Affected
Affected products and packages — 2 rows
| Vendor | Product / Package | Ecosystem | Version introduced | Fixed |
|---|
| netty | netty | — | >= 4.2.0.Alpha1, < 4.2.13.Final | — |
| io.netty | netty-codec-http | — | >= 4.2.0.Alpha1, < 4.2.13.Final | — |
About this page
This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-42584 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Wednesday, August 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.