Twentig <= 1.9.7 - Authenticated (Contributor+) Stored Cross-Site Scripting via 'featuredImageSizeWidth'

The Twentig plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'featuredImageSizeWidth' parameter in versions up to, and including, 1.9.7 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.