A flaw was found in fast-uri. The library incorrectly processes Uniform Resource Identifier (URI) hosts containing unbalanced brackets, leading to a discrepancy in how the host is parsed by fast-uri compared to other HTTP clients. This host confusion can allow an attacker to bypass security policies, such as Server-Side Request Forgery (SSRF) denylists or redirect allowlists, by causing an application to evaluate its policy against an incorrect host string. This could result in unintended network requests or access to unauthorized resources.