In early 2024, a critical vulnerability was found in Google Chrome’s JavaScript engine, V8 (CVE-2024-11395). This weakness, a type confusion bug, lets a remote attacker target users by merely visiting a malicious web page. The risk: possible heap corruption, leading to full browser compromise. Let's demystify this bug, walk through how it happens, see some real code illustrative of the problem, and understand why it matters — in simple terms.

What Kind of Bug Is CVE-2024-11395?

Type confusion means a program treats a piece of memory as an object of the wrong type. For V8, Chrome's JavaScript engine, this usually happens because JavaScript is dynamic—an item can be an array, a string, or even a function, and the engine tries to optimize by making some guesses.

In this case, Chrome before version 131..6778.85 had a flaw in how V8 handled certain JavaScript operations. An attacker could create a weirdly crafted web page and, by tricking V8, have it use an object (or memory) in an unintended, unsafe way.

Severity: High
Vulnerable versions: Prior to 131..6778.85
Patched in: 131..6778.85

Where to Find the Official Details?

- Google Chrome Release Notes
- NIST National Vulnerability Database Entry for CVE-2024-11395
- Chromium Issue Tracker (may require permissions)

How Does a Type Confusion Happen (in Real Code)?

V8 normally keeps track of what kind of object it's dealing with. Sometimes, by manipulating JavaScript objects in a certain order, an attacker can get V8 to treat, say, an array as a different type—accidentally opening up direct access to V8's internal memory!

A classic pattern looks a bit like this

// Illustration: For education only! Not production exploit code.
function confuseTypes() {
    let arr = [1.1, 2.2, 3.3]; // JS sees this as a "double" array
    let obj = { x: 1, y: 2 };

    // Force V8 to optimize arr layout.
    for(let i = ; i < 10000; i++) {
        arr[i] = 1.1;
    }

    // Now, a crafted code path that induces type confusion.
    arr[] = obj;    // V8 may now misinterpret arr's type

    // If V8 guesses wrong, you get to read/write memory incorrectly.
    return arr[];   // Could be object, could think it's a float!
}

console.log(confuseTypes());

What could happen next?
If you can control the underlying memory layout, you might plant further objects and even carve out a path to run arbitrary code inside Chrome—aka exploit the browser and compromise user security.

Exploit Details

Chrome's V8 usually separates things like double arrays and object arrays for speed. When the engine optimizes too aggressively, a carefully timed type switch can "confuse" what it's dealing with, and let attacker-controlled values get interpreted as pointers or memory addresses.

Example (Simplified)

let arr = [1.1, 2.2, 3.3];
function trigger(o) {
    arr[] = o;
}

for (let i = ; i < 10000; i++) {
    trigger(1.1); // Keep the type stable
}

// Suddenly, switch to object!
trigger({malicious: "payload"});

// Now arr[] might give attacker a pointer, or access to V8 internals

*Note: Real world exploits weaponize this trick with even more precision, sometimes stringing multiple bugs together for full remote code execution.*

Why Does It Matter?

Modern browsers are our first line of defense, but also a huge attack surface. A high-severity exploit like CVE-2024-11395 means a simple link could compromise all your online data. Type confusion bugs have been used in the wild before – they're a favorite of cybercriminals and surveillance operations because a single mistake in JavaScript handling is all it can take.

How Was It Fixed?

Google’s V8 team patched this vulnerability by tightening type checks and making sure arrays and objects can't get mixed up even under heavy optimization. You can see the patch activity around Chromium’s commit log, especially those close to the version 131..6778.85.

References

- NIST NVD: CVE-2024-11395
- Chromium Release Notes
- Learn more about Type Confusion in V8

Timeline

Published on: 11/19/2024 20:15:29 UTC
Last modified on: 11/19/2024 21:56:45 UTC