Critical V8 Type Confusion Vulnerabilities in Chrome and Solutions

 Type Confusion in Chrome's V8 Engine

Overview

Two critical vulnerabilities, CVE-2025-8011 and CVE-2025-8010, were disclosed on July 22, 2025, affecting Google Chrome prior to version 138.0.7204.168. Both vulnerabilities stem from type confusion in the V8 JavaScript engine, allowing remote attackers to potentially exploit heap corruption via a maliciously crafted HTML page. Chromium classifies these vulnerabilities as High severity.

Technical Background

What is V8?

V8 is Google’s open-source JavaScript engine used in Chrome and Node.js. It compiles JavaScript to machine code for high-performance execution. However, improper handling of JavaScript objects can lead to type confusion, where the engine misinterprets an object's type, leading to memory corruption.

Type Confusion Vulnerability

Type confusion occurs when an object is treated as one type when it is actually another. In V8, this can happen due to:

• Incorrect optimizations in TurboFan (V8’s optimizing compiler).
• Improper object property access leading to memory misinterpretation.
• Failure to validate types after JIT compilation.

Attackers can exploit this to corrupt memory, execute arbitrary code, or bypass security mechanisms.

CVE-2025-8011 & CVE-2025-8010: Exploitation Scenarios 

Both vulnerabilities involve crafted HTML pages triggering type confusion in V8. Below are possible exploitation scenarios:

Scenario 1: Malicious Website Triggers Heap Corruption

1. Attacker creates a malicious webpage with JavaScript designed to confuse V8’s type system.
2. Victim visits the page using Chrome (< 138.0.7204.168).
3. JavaScript executes, exploiting type confusion to corrupt heap memory.
4. Attacker gains control over the corrupted memory, potentially leading to remote code execution (RCE).

Sample Exploit Code (Hypothetical)

// Hypothetical PoC triggering type confusion
function triggerTypeConfusion() {
    let arr = [1.1, 2.2, 3.3];
    let obj = { a: 1 };

    // Force TurboFan optimization
    for (let i = 0; i < 100000; i++) {
        // Manipulate object types to confuse V8
        if (i === 99999) {
            arr.__proto__ = obj;
        }
    }

    // Access array as if it were still a float array
    return arr[0]; // May read corrupted memory
}

// Execute the exploit
let corruptedValue = triggerTypeConfusion();
console.log(corruptedValue); // Could leak memory or crash

(Note: This is a simplified example; real exploits are more complex.)

Scenario 2: Browser Sandbox Escape

If combined with another vulnerability (e.g., a sandbox escape), an attacker could:

1. Exploit type confusion to gain arbitrary read/write in the renderer process.
2. Chain with a sandbox bypass to execute code outside Chrome’s restricted environment.
3. Fully compromise the system.

Mitigation & Fixes 

Google addressed these issues in Chrome 138.0.7204.168 by:

• Improving type checks in V8’s TurboFan compiler.
• Adding stricter validation for object property accesses.
• Introducing runtime hardening against heap corruption.

Recommendations

• Update Chrome immediately to the latest version.
• Enable automatic updates to ensure protection against future vulnerabilities.
• Use exploit mitigations like Control Flow Integrity (CFI) and Site Isolation.

Conclusion 

CVE-2025-8011 and CVE-2025-8010 highlight the risks of type confusion in JavaScript engines. Attackers can exploit these flaws to achieve heap corruption and possibly RCE. Users must update their browsers and remain vigilant against malicious websites. Developers should adopt secure coding practices to prevent similar issues in the future.

For more details, refer to:

• Chromium Security Advisory

Stay secure! 🚀