The vulnerability description explicitly states that converter.rb in md2pdf allows command injection via filenames. This indicates the file contains a function that passes user-controlled filenames directly into shell commands without proper sanitization. The most probable location is the main conversion function (likely named 'convert') that processes filenames. Ruby's common command execution patterns (system/backticks) would make this vulnerable when interpolating untrusted input. While the exact code isn't available, the CVE description and file path provide strong contextual evidence.