Contextual Related Posts <= 4.2.1 - Authenticated (Contributor+) Stored Cross-Site Scripting via 'other_attributes'

The Contextual Related Posts plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'other_attributes' parameter in versions up to, and including, 4.2.1 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.