The vulnerability stems from improper sanitization of ID numbers in quiz override screens. Moodle's quiz override functionality handles user/group overrides, and the ID number (user-supplied field) was displayed without adequate escaping. The 'quiz_override_row' function would be responsible for generating table rows in override interfaces, making it the most likely location where raw ID numbers were rendered. The vulnerability type (stored XSS) and affected component (quiz overrides) strongly correlate with this rendering function. While exact code isn't available, Moodle's architecture patterns and the vulnerability description indicate this as the primary candidate.