The provided information lacks concrete technical details about the implementation of Ghost CMS's file upload module. While the vulnerability (CWE-434) indicates insufficient file type validation, there is no access to:- 1) Specific code snippets from Ghost v4.42.0, 2) GitHub patch/diff information, or 3) File path/function names from vulnerability reports. The vendor's security documentation mentions intentional trusted-user uploads but doesn't reveal implementation details. Without these critical artifacts, we cannot confidently identify specific vulnerable functions. Arbitrary file upload vulnerabilities typically involve file handling functions, but precise identification requires code analysis unavailable in the provided materials.