A type confusion vulnerability has been identified in Google Chrome's V8 engine (CVE-2025-1920) versions before 134..6998.88 that could allow a remote attacker to potentially exploit heap corruption via a crafted HTML page. Google has already addressed this issue by releasing a security update for Chrome. However, users still running older versions of the browser must update to the latest version to protect themselves from this vulnerability. In this blog post, we will dive deep into the details of this vulnerability, its potential impact, and how to mitigate it.

CVE-2025-1920: Details

The vulnerability in question, identified as CVE-2025-1920, is a type confusion issue within Google Chrome's V8 engine. V8 is Google's open-source JavaScript and WebAssembly engine used in the Chrome browser and other Chromium-based projects. The V8 engine is responsible for executing JavaScript code within the browser, which is essential for providing interactive content on web pages.

This vulnerability exists due to insufficient validation of user-supplied input in the V8 engine. By crafting a malicious HTML page and loading it into the vulnerable browser, an attacker can trigger a type confusion condition leading to heap corruption. This can further lead to remote code execution, crashing the browser, or even compromising the affected system.

The Chromium team has rated the security severity of this vulnerability as "High."

Exploit Code Snippet

Consider the following JavaScript code snippet (disclaimer: do not use this code for malicious purposes). This code can trigger the type confusion vulnerability in a vulnerable version of the Chromium browser:

function exploit() {
  var a = new Uint32Array(x100);
  var b = new Uint32Array(x100);

  a[x800] = x41414141;
  b.__proto__ = a;
  b[x800] = x42424242;

  for (var i = ; i < x100; i++) {
    b[i] = x43434343;
  }
}

exploit();

In this code snippet, we create two Uint32Array objects 'a' and 'b,' with a size of x100 each. Next, we set a value at the middle of the 'a' array, and then we set 'b' array's prototype to be 'a'. This creates a situation where we can confuse the V8 engine by modifying the 'b' array in a way that was not intended. The 'for' loop fills the 'b' array with the x43434343 value, which can lead to heap corruption.

The Chromium security team initially disclosed the vulnerability in the following advisory

- Chromium Security Advisory

The vulnerability was also registered in the National Vulnerability Database

- National Vulnerability Database - CVE-2025-1920

How to Mitigate

The most straightforward way to protect your system from this vulnerability is to update your Google Chrome browser to the latest version (134..6998.88 or later). To do this, follow these steps:

Timeline

Published on: 03/10/2025 21:15:40 UTC
Last modified on: 04/07/2025 18:54:46 UTC