The Prismatic plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'prismatic_encoded' pseudo-shortcode in all versions up to, and including, 3.7.3. This is due to insufficient input sanitization and output escaping on user-supplied attributes within the 'prismatic_decode' function. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page by submitting a comment containing a crafted 'prismatic_encoded' pseudo-shortcode.