The Hostel plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'custom_currency' parameter and the 'locale_url' setting in all versions up to, and including, 1.1.8 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with Administrator-level access, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This only affects multi-site installations and installations where unfiltered_html has been disabled.