CVE-2020-6418

What is Chromium's V8 Engine?

V8 is the JavaScript and WebAssembly engine at the core of Google Chrome and every other Chromium-based browser, executing the JavaScript on every web page a user visits. Because it runs untrusted, attacker-supplied code by design, type-confusion and memory-safety bugs in V8 are a direct and reliable path to remote code execution in the browser renderer.

Overview

CVE-2020-6418 is a type confusion vulnerability (CWE-843) in V8 that allows heap corruption exploitation via a crafted HTML page (CVSS 3.1: AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H, 8.8 High). Google shipped an emergency stable channel update on February 24, 2020, explicitly acknowledging exploitation in the wild — one of the earliest confirmed Chrome 0-days of that year, setting the tone for the pattern of actively-exploited V8 bugs (see also CVE-2020-16009 and CVE-2020-16013, also enriched on this site) that continued through the rest of 2020.

Technical Details

A type confusion bug occurs when V8's internal engine logic treats a value as one JavaScript type when it's actually a different, incompatible type at the machine level, allowing carefully crafted JavaScript to corrupt heap memory in an attacker-controlled way. Because the bug lives in V8 itself, it affects every Chromium-based browser — Chrome, Edge, Opera, and others — not just Google's own product, requiring coordinated updates across the ecosystem.

Discovery

Identified through Google's internal security research process; Google's advisory for the February 24, 2020 release explicitly noted awareness of an exploit for this vulnerability existing in the wild.

Exploitation Context

CISA added this CVE to KEV in November 2021 based on confirmed exploitation. Being among the earliest acknowledged Chrome 0-days of 2020, this vulnerability set the pattern for a year that would see several more actively-exploited V8 bugs, reflecting sustained attacker interest in browser JavaScript engines as a reliable initial-access vector.

Remediation

1. Update Chrome and any other Chromium-based browser to the version including the February 24, 2020 fix or later — this should occur automatically via browser auto-update.
2. Enable and verify Site Isolation in your browser deployment as defense-in-depth against renderer-level compromise.
3. Don't disable browser auto-update mechanisms in managed enterprise environments, given how frequently V8 0-days were confirmed exploited throughout 2020.
4. Treat any system running an unpatched Chromium-based browser through February 2020 as a potential compromise candidate given the confirmed active-exploitation status.