WP Fastest Cache vulnerabilities

The WP Fastest Cache plugin for WordPress in versions up to and including 1.5.3 is vulnerable to Sensitive Information Exposure. The plugin caches the response of wp-activate.php without honoring its no-store/no-cache headers, the wp-activate-* cookie, or the WP_INSTALLING state, writing the credential-bearing activation response to a publicly accessible cache file. This allows unauthenticated attackers to retrieve the plaintext username and twelve-character password of the most recently activated Multisite registrant from that cached response.

The WP Fastest Cache WordPress plugin before 1.5.1 does not include a set of tracking-related query parameters in its page-cache key while still caching pages requested with them, allowing unauthenticated attackers to have a page rendered under their own request context stored under, and served from, the clean URL's cache entry to every subsequent visitor.

The WP Fastest Cache plugin for WordPress is vulnerable to Stored Cross-Site Scripting via HTTP Host Header in all versions up to, and including, 1.5.0 due to insufficient input sanitization and output escaping. Unauthenticated attackers can inject arbitrary web scripts that execute when a user accesses an injected page. This requires the Polylang or Polylang Pro plugin to be active and the Combine JS option enabled.

The WP Fastest Cache WordPress plugin before version 1.5.1 does not validate the Host header before using it to build URLs of asset files embedded in cached pages and does not include that header in the cache key, allowing unauthenticated attackers to poison cached pages with references to a server they control and have arbitrary JavaScript run for every subsequent visitor.

The WP Fastest Cache plugin for WordPress is vulnerable to unauthorized modification of data due to a missing capability check on the wpfc_db_fix_callback() function. This affects all versions up to and including 1.4.0 and only sites with premium activated.