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: HTTP/1.0 TE+CL Coexistence Bypasses Smuggling Sanitization
AV AC PR UI S C I A CVSS EPSS %ile KEV
N L N N U H H H 9.8 .0063 47.5 —
AFFECTED
Product Versions Fixed
netty >= 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-2026-42581 (netty). Public exploit reference added.
Aug 13 RESCORED — CVE-2026-42581 (netty). CVSS 5.8 → 9.8 (NVD).
Description
Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, HttpObjectDecoder strips a conflicting Content-Length header when a request carries both Transfer-Encoding: chunked and Content-Length, but only for HTTP/1.1 messages. The guard is absent for HTTP/1.0. An attacker that sends an HTTP/1.0 request with both headers causes Netty to decode the body as chunked while leaving Content-Length intact in the forwarded HttpMessage. Any downstream proxy or handler that trusts Content-Length over Transfer-Encoding will disagree on message boundaries, enabling request smuggling. 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-2026-42581 (netty). Public exploit reference added. |
| August 13, 2026 | RESCORED | RESCORED — CVE-2026-42581 (netty). CVSS 5.8 → 9.8 (NVD). |
Affected
Affected products and packages — 1 row
| Vendor | Product / Package | Ecosystem | Version introduced | Fixed |
|---|
| netty | netty | — | >= 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-2026-42581 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.