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Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

CVE-2026-42584

High
9.1/10

Summary

Netty is an asynchronous, event-driven network application framework. Prior to 4.1.133.Final and 4.2.x prior to 4.2.13.Final and 5.0.0.Alpha1 and 5.0.0.Alpha2, 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 messages 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.

  • LOW
  • NETWORK
  • HIGH
  • UNCHANGED
  • NONE
  • NONE
  • NONE
  • HIGH

CWE-444 - HTTP Request Smuggling

Entities such as web servers, web caching proxies, and application firewalls could parse HTTP requests differently. When there are two or more such entities in the path of an HTTP request, an attacker can send a specially crafted HTTP request that is seen as two different sets of requests by the attacked devices, allowing the attacker to smuggle a request into one device without the other device being aware of it. Such a vulnerability can prove devastating, for it enables further attacks on the application, like web cache poisoning, session hijacking, cross-site scripting, security bypassing, and sensitive information exposure.

References

Advisory Timeline

  • Published