Per-Site CageFS Isolation Now Available in Beta for CloudLinux Customers

Updated February 26, 2026: This article has been updated to reflect changes introduced in Phase 2 of Website Isolation. Key changes: --site-isolation-allow command has been renamed to --site-isolation-allow-all; end users can now enable isolation for their own domains (previously admin-only). See the Phase 2 announcement for full details.

Update on Feb 5, 2026: Added details about partial PHP-FPM support.

We are announcing the beta release of Per-Site CageFS Isolation, a new feature designed to enhance security within multi-site accounts. Available at no additional cost to existing CloudLinux customers, this release marks the first phase of our comprehensive Website Isolation project.

What is Website Isolation?

Currently, CloudLinux provides user-level isolation through CageFS, ensuring that users on a server cannot access each other's files. With Website Isolation, we're taking this a step further by enabling isolation between websites within the same user account.

Ideal Use Cases

Website Isolation is valuable for any environment where customers run multiple sites under a single account. This includes:

• Shared hosting: Standard shared hosting accounts where a user hosts a primary domain alongside several addon domains.
• VPS hosting: Single-tenant VPS environments where an end customer or agency manages multiple websites under one account.
• Staging: Scenarios where a user needs to test updates or changes on a staging subdomain without risking the stability or security of the production site.

Value for End Customers

This new feature delivers direct value to end customers:

• Enhanced security: If one website is compromised, the attacker cannot access files belonging to other websites on the same account. The damage is contained within the single isolated environment.
• Safe development: Users can treat staging sites as fully isolated entities, ensuring production environments remain protected during development and testing.

How Hosting Providers Benefit

In addition to enhancing the customer experience, hosting providers also benefit through:

• Reduced support load: By preventing cross-site contamination within user accounts, this feature reduces the spread of malware. This minimizes the complexity and effort required for cleanups, saving valuable support time.
• Improved server stability: Isolating websites helps prevent a single vulnerable site from affecting the integrity of other sites hosted by the same customer, leading to a more stable overall platform.

What's Included in This Release

This beta release delivers the following capabilities:

• File system isolation per site: Each website operates in its own isolated environment and cannot see or access files from other websites belonging to the same user.
• Flexible activation: Server administrators can enable isolation for specific domains via CLI, or allow end users to manage isolation for their own domains

Compatible PHP Handlers

Compatible PHP Versions

Website Isolation provides partial FPM handler support for ea-php (cPanel). The following ea-php versions are compatible:

Quick Start

Installation

Install the beta version from the testing repository:

yum install cagefs --enablerepo=cloudlinux-updates-testing

Minimum Package Versions

Enable Website Isolation

1. Enable the feature server-wide (administrator, one-time setup):cagefsctl --site-isolation-allow-all

cagefsctl --site-isolation-enable example.com