The Twittee Text Tweet plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'id' shortcode attribute in all versions up to and including 1.0.8. This is due to insufficient input sanitization and output escaping on user-supplied shortcode attributes. The ttt_twittee_tweeter() function uses extract() to pull shortcode attributes into local variables and then directly concatenates them into HTML output without any escaping. Specifically, the $id parameter is inserted into an HTML id attribute context without esc_attr(), allowing an attacker to break out of the attribute and inject arbitrary HTML event handlers. Additionally, the $tweet, $content, $balloon, and $theme attributes are similarly injected into inline JavaScript without escaping (lines 87, 93, 101, 117). This makes it possible for authenticated attackers, with Contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.