Riskcovery

CVE-2026-42581

Netty: HTTP/1.0 TE+CL Coexistence Bypasses Smuggling Sanitization

State
Published
Severity
5.8 Medium
Published
May 13, 2026
Updated
Sep 18, 2026
Reserved
Apr 28, 2026

Read the record on cve.org

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.

Scores

CVSSScoreVectorSource
3.15.8 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:NGitHub_M
3.17.2 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:Nredhat-SADP

Weaknesses

  • CWE-444 Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

Affected Products

ProductVersions
nettynetty
  • >= 4.2.0.Alpha1, < 4.2.13.FinalAffected
  • < 4.1.133.FinalAffected

References

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