CVE-2026-104021: Fastcache by Host.it: Code Injection (CVSS 7.2)

Fastcache by Host.it: Code Injection

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.

Description from the National Vulnerability Database, published by Wordfence

What it means for a small business

Fastcache by Host.it is a WordPress plugin. If your website uses it, the flaw is on your site whether or not anyone has noticed yet: attackers scan the whole internet for the plugins with published flaws, usually within days of a record like this one going public.

Most small-business sites run 15 to 40 plugins, and few owners know the list. You can check from WordPress itself (Plugins, then Installed Plugins), or let our free plugin check look it up by name.

How likely is an attack? The Exploit Prediction Scoring System, run by FIRST (the global association of security response teams), puts the odds of this one being exploited in the next 30 days at 0.39%, higher than 32% of CVEs. That’s low, but low isn’t zero, and the odds jump the day someone publishes an exploit. Scored October 29, 2026, updated daily.

Check your own setup

Is Fastcache by Host.it safe? Every recorded flaw in it, the version that fixes each, and whether it’s still maintained.
Website check: reads what your site runs from the outside (WordPress version, plugins it can see, old server software) and matches it against this database.
Server check: what your web server says about itself, and whether that version has known flaws.

Sources

Part of the Huttenlocher Technologies vulnerability database, refreshed twice a day from CISA and the NVD. The title, category and plain-language guidance are ours; check the linked record before acting on a detail. This is general guidance, not a review of your systems.

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