CVE-2026-15790: Video Gallery <= 4.0.4 - Authenticated (Author+) Stored Cross-Site Scripting via Attachment 'post_title' via emd_mb_meta Shortcode

The Youtube Showcase plugin for WordPress is vulnerable to Stored Cross-Site Scripting in versions up to, and including, 4.0.4 via the 'emdmbmeta' shortcode. This is due to insufficient input sanitization and output escaping on attachment titles referenced by the shortcode's image field: EMDMBHelper::imageinfo() returns the attachment's raw posttitle, and EMDMBHelper::shortcode() interpolates it into title="%s" HTML attributes via sprintf() without escattr(). This makes it possible for authenticated attackers, with author-level access and above (uploadfiles capability required to create the attachment, editposts/publishposts to embed the shortcode), to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.