The vulnerability stems from missing capability checks in the procedural code flow of mod/lti/ajax.php, not from specific named functions. The original code processed the 'search' action without verifying the 'moodle/course:manageactivities' and 'mod/lti:addinstance' capabilities. The patch added require_capability() calls directly in the script's main logic, indicating the vulnerability resided in the absence of these checks in the procedural flow. Since the issue is tied to the script's structure rather than discrete functions, no specific functions are identified.