Sunshine Photo Cart < 3.7.4 - Unauthenticated Content Injection via sunshine_modal_add_comment()

The Sunshine Photo Cart WordPress plugin before 3.7.4 does not check whether a visitor is permitted to access a restricted gallery before accepting comment submissions for its images, while it does perform that check when displaying comments, allowing unauthenticated attackers to inject attacker-chosen content with a chosen author name and email into galleries the owner has restricted (password-protected, email-gated, private, account-only or expired).