The jQuery Hover Footnotes plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Footnote Qualifier ('{{...}}' Syntax) in all versions up to, and including, 1.4 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 attribute-breakout payload (e.g., a double-quote followed by an event handler) contains no angle brackets and therefore bypasses WordPress core's wp_kses_post() filtering, which only strips disallowed HTML tags rather than sanitizing attribute contexts.