CVE-2026-42584

Summary

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.

Affected Software

VendorProductVersion RangeStatus
nettynetty>= 4.2.0.Alpha1, < 4.2.13.Finalaffected
nettynetty< 4.1.133.Finalaffected
io.nettynetty-codec-http>= 4.2.0.Alpha1, < 4.2.13.Finalaffected
io.nettynetty-codec-http< 4.1.133.Finalaffected

Weaknesses

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

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: poc
    • Automatable: yes
    • Technical Impact: partial

Additional References

netty: io.netty/netty-codec-http: Netty: Incorrect HTTP response parsing leads to data confusion

Additional References

References