Overview
CVE-2023-6699 is a high-severity vulnerability identified in the V8 JavaScript engine used by Chromium-based browsers such as Google Chrome, Microsoft Edge, and others. The flaw resides in the WebAssembly (Wasm) implementation, allowing attackers to potentially execute arbitrary code outside the intended sandbox, resulting in full system compromise when combined with other exploits.
Given V8’s widespread use across browsers and JavaScript runtimes, this vulnerability represents a significant security threat, particularly in highly targeted environments like enterprise workstations, zero-day markets, and surveillance contexts.
Vulnerability Summary
| Field | Detail |
|---|---|
| CVE ID | CVE-2023-6699 |
| Severity | High (CVSS Score: 8.8) |
| Attack Vector | Remote (via malicious web content) |
| Privileges Required | None |
| User Interaction | Required (visiting a malicious webpage) |
| Impact | Sandbox escape → Arbitrary Code Execution |
Affected Products
| Product | Affected Versions |
|---|---|
| Google Chrome | Prior to 119.0.6045.123 |
| Microsoft Edge | Versions using vulnerable V8 |
| Chromium Embedded | Any build using affected V8 |
| Electron apps | Using outdated Chromium core |
How the Exploit Works
The vulnerability originates from incorrect memory handling in the WebAssembly component of the V8 JavaScript engine. WebAssembly, designed to offer near-native performance inside the browser, is sandboxed by default to prevent arbitrary memory access. However, CVE-2023-6699 exploits a bug in bounds checking and memory management that allows a malicious WebAssembly module to escape its intended memory sandbox.
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This sandbox escape enables the attacker to read/write memory outside the Wasm instance, leading to arbitrary code execution in the browser process.
Although CVE-2023-6699 on its own doesn’t provide full system access, it is highly valuable when chained with other vulnerabilities (e.g., a renderer-to-kernel exploit) for full exploitation.
Conceptual Exploit Scenario
A conceptual example involves a website embedding a crafted WebAssembly module:
When a user visits the malicious site, the Wasm code bypasses memory protections and executes unintended behavior within the browser.
Recommendations for Mitigation
To protect against CVE-2023-6699, all users and administrators are strongly advised to:
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Update Browsers Immediately
Ensure Chrome, Edge, Brave, and other Chromium-based browsers are updated to the latest version (119.0.6045.123 or higher). -
Patch Electron-Based Applications
If using Electron apps, ensure they are built with an up-to-date version of Chromium/V8. -
Disable WebAssembly in Sensitive Contexts
In high-security environments, consider temporarily disabling WebAssembly via browser flags or content security policies (CSP). -
Use Script Isolation and Site Sandboxing
Enforce origin isolation and useCross-Origin-Opener-PolicyandCross-Origin-Embedder-Policyheaders to limit exploit surface. -
Employ Threat Detection and EDR
Use endpoint detection tools that can monitor for abnormal behavior tied to browser processes or native code execution.
Timeline and Response
-
Reported: November 2023
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Patched in Chromium: December 2023 (v119.0.6045.123)
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Google Project Zero Involvement: Confirmed
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Public Exploitation: No known active exploits at the time of publication, but highly likely to be targeted
Closing Thoughts
CVE-2023-6699 is another demonstration of the ongoing risks posed by highly complex JavaScript engines and WebAssembly runtimes. As performance demands and browser capabilities continue to grow, so too does the attack surface available to advanced threat actors.
Developers and organizations are urged to follow defense-in-depth principles, limit exposure to just-in-time compilation and WebAssembly where unnecessary, and maintain a proactive update policy to stay protected.