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

CVE-2026-23527

High
9.8/10

Summary

H3 is a minimal HTTP framework built for high performance and portability. In versions prior to 1.15.5, there is a critical HTTP Request Smuggling vulnerability. The "readRawBody()" function performs a strict, case-sensitive check for the Transfer-Encoding header. It explicitly looks for "chunked", but according to the RFC, this header is case-insensitive.

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