Google Chrome Site Isolation Use-After-Free Sandbox Escape Vulnerability (CVE-2020-16017)

1. Vulnerability Overview & Root Cause

This vulnerability (CVE-2020-16017) is a critical Use-After-Free (UAF) memory corruption flaw residing within the Site Isolation mechanism of Google Chrome. Site Isolation is a fundamental security boundary designed to ensure that pages from different websites are put into separate processes. However, a logical flaw in managing object lifecycles during cross-process communication allows an attacker to reference memory that has already been deallocated, leading to unstable memory states and potential code execution.

2. Exploitation Mechanics & Attack Scenario

The exploitation of this vulnerability typically occurs in a multi-stage attack chain. First, the attacker compromises the renderer process (e.g., via a separate V8 engine vulnerability or malicious script execution). Once inside the renderer, the attacker sends specifically crafted IPC (Inter-Process Communication) messages to the browser process, targeting the Site Isolation components. This triggers a Use-After-Free condition in the browser process, allowing the attacker to hijack the control flow, escape the browser sandbox, and execute arbitrary commands with the privileges of the logged-in user.

3. Infrastructure & Business Impact

As a vulnerability listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, CVE-2020-16017 poses a severe threat to enterprise environments. Successful exploitation allows drive-by downloads where a user merely visiting a compromised or malicious website can result in full endpoint compromise. This can serve as an initial access vector for ransomware deployment, lateral movement within corporate networks, and sensitive data exfiltration.