Refitter is a tool for generating a C# REST API client using the Refit library. Prior to 2.1.2, the header parameter name in "parameters[].name" with "in: header" is emitted verbatim into a Refit "[Header("<name>")]" attribute string without escaping quotation marks. An attacker-influenced OpenAPI description can pass default validation without "--skip-validation" and break out from the parameter-list position by closing the parameter and method syntax, attribute, interface, and namespace. The generated file can remain valid C# while containing a top-level file class with a "[ModuleInitializer]" method, which executes attacker code when the compiled assembly is loaded at application startup, even if the client is never called. Query "AliasAs" and enum/default value sinks are escaped; this flaw is in header-name attribute-string emission. The behavior was verified with Refitter 2.0.0 and .NET 8. This issue is fixed in version 2.1.2.