Browser Sandbox.

An OS-level isolation layer that confines a browser's renderer and helper processes so that compromised web code cannot read the file system or other applications. It belongs to the Application Security category of cybersecurity.

An OS-level isolation layer that confines a browser's renderer and helper processes so that compromised web code cannot read the file system or other applications.

A browser sandbox is the set of operating-system mechanisms that the browser process uses to constrain less-trusted child processes — renderers, GPU process, plugins, network service — to a minimal set of capabilities. Chromium uses Windows job objects and integrity levels, macOS Seatbelt, and Linux seccomp-bpf plus namespaces; Firefox uses similar primitives. Even if attacker JavaScript or a renderer-level memory corruption succeeds, the sandbox prevents arbitrary file access, command execution, or interaction with other processes without an additional sandbox escape. Together with Site Isolation, the sandbox is the modern browser's primary defense against drive-by exploits, and is regularly stress-tested at Pwn2Own where a full sandbox-escape chain is required to win.

Defences for Browser Sandbox typically combine technical controls and operational practices, as detailed in the full definition above.

Common alternative names include: Renderer sandbox.