The VikRentItems – Flexible Rental Management System plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the customer email field of the booking checkout form in versions up to, and including, 1.2.1. This is due to insufficient input sanitization and output escaping in the saveorder() function, which stores the raw email value via VikRequest::getString() (applying only sanitize_text_field(), which does not neutralize HTML attribute-breaking characters such as double quotes), and in the editorder template which echoes the stored custmail value into an HTML input element's value attribute without esc_attr(). This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.