The Download Manager plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'file[additional_previews][]' parameter in all versions up to, and including, 7.6.3 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with author-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The wpdm_sanitize_array() function strips HTML tags via wp_kses but leaves bare single quotes intact and calls stripslashes_deep() which defeats WordPress magic quotes protection, allowing a single-quote-based attribute breakout payload to be stored verbatim and later rendered without escaping.