The Instant-Quote.co Quotation Page plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Shortcode Attributes in all versions up to, and including, 1.3.4 due to insufficient input sanitization and output escaping. 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. A Contributor-level user can trigger execution against higher-privileged users by embedding the malicious shortcode in a post submitted for review, causing the injected scripts to execute when an administrator previews or views the post.