AIKIDO-2025-10638

github.com/valyala/fasthttp is vulnerable to Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

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

Low Risk

This Affects:

github.com/valyala/fasthttp

1.0.0 - 1.65.0

Fixed in 1.66.0

TL;DR

Affected versions of this package are vulnerable to Cache Poisoning via Incorrect HTTP Request Parsing due to a violation of RFC 9112 where the HTTP request line parser would incorrectly include extra whitespace characters as part of the request URI; when deployed behind a caching proxy, an attacker could exploit this by sending a request containing whitespace, which the proxy would interpret as a unique resource and cache the response, potentially allowing the poisoning of the cache for a legitimate URL without whitespace.

Who does this affect?

You are affected if you are using a version that falls within the vulnerable range.

Background info

github.com/valyala/fasthttp is vulnerable to Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') in versions 1.0.0 - 1.65.0.