Fastcache by Host.it <= 1.7.4 - Authenticated (Administrator+) Code Injection via .htaccess Directive Injection via 'cache_cookie_exclude' Setting

Summary

The Fastcache by Host.it plugin for WordPress is vulnerable to Code Injection in all versions up to, and including, 1.7.4 via the `fastcache_settings[cache_cookie_exclude][]` parameter. This is due to the plugin registering the `cache_cookie_exclude` setting via `register_setting()` without a `sanitize_callback`, while `buildSiteHtaccessRules()` applies only `trim()` to each cookie value before interpolating it directly into an Apache `RewriteCond` line — a normalization that strips surrounding whitespace but leaves embedded newlines intact, allowing an attacker to break out of the capture group and append arbitrary directives. This makes it possible for authenticated attackers, with administrator-level access and above, to inject arbitrary Apache directives into the site's `.htaccess` file via `file_put_contents()`, enabling server-level configuration changes such as setting `php_value auto_prepend_file` to execute attacker-controlled PHP code on every request.

Timeline

1. Oct 10, 2026, 4:26 AM UTCCVE published
2. Oct 11, 2026, 4:41 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: total

3. Oct 11, 2026, 4:55 PM UTCRecord last updated

Affected versions

• hostspa Fastcache by Host.it

  through 1.7.4

References 7