CVE-2025-25000 - Type Confusion in Microsoft Edge (Chromium-Based) Lets Attackers Run Code Remotely

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Microsoft Edge is the default web browser for Windows 10 and 11. Since it’s based on Chromium (the same core as Chrome), most vulnerabilities in Chromium end up making Edge vulnerable too. One of the latest and most serious of these bugs is CVE-2025-25000. In this long-form post, I’ll explain everything you need to know about it: what “type confusion” means, how this bug works, how it can be exploited, and what you can do about it.

*This post uses simple, clear language and includes practical code and references for defenders and security professionals.*

What Is CVE-2025-25000?

CVE-2025-25000 is a type confusion vulnerability present in Microsoft Edge, specifically the Chromium-based version. It allows unauthorized attackers to execute arbitrary code remotely. In plain English: a hacker can send you a link, and if you open it in Edge, there’s a chance they could take control of your computer or run malicious code — even if you don't download anything.

Official References

- Microsoft Security Advisories Portal
- Chromium Issue Tracker – Sample Type Confusion Bugs
- Common Vulnerabilities and Exposures: CVE-2025-25000 (Mitre)

Understanding Type Confusion

In programming, “type confusion” happens when a piece of code uses data of one type (like a string or integer) as if it were a different type. Imagine trying to treat a house key as a car key — you might get into trouble.

In JavaScript Engines

Edge is built on Chromium, which uses the V8 JavaScript engine. In V8, type confusion often happens when Just-In-Time (JIT) (fast) compiled code makes wrong assumptions about object types, letting hackers trick the engine into reading or writing arbitrary memory.

Here’s a simplified example to demonstrate type confusion in a JavaScript engine

function typeConfusion(arr, value) {
  arr[] = 1.1;       // arr is now a float array
  arr[1] = value;      // Place attacker-controlled value!

  // JIT compiler assumes all elements are floats, but...
}

let o = {a: 42};        // Attacker-controlled object
typeConfusion([,], o);
// o is now placed in a buffer where code expects a number!
// This can lead to arbitrary code execution.

In a real attack, the attacker would chain this to write malicious payloads into memory locations of their choice.

How Could This Be Exploited?

Remote Code Execution (RCE):
By crafting a malicious webpage or ad, a remote attacker can exploit this bug so that, when you visit the page in Edge, they can:

Use your computer in botnet attacks

The victim only needs to *visit* a website in Edge — no downloads or extra clicks required.

Proof-of-Concept (POC) Code

*Warning: For educational use by security professionals!*

// Note: This is a HIGHLY simplified pattern
function triggerTypeConfusion() {
  let arr = [1.1, 1.2, 1.3];
  let obj = {mark: "owned"};
  arr[] = obj;
  // JIT compiler may treat arr as a float array,
  // but this inserts an object, resulting in type confusion.
  // Real POC code would manipulate memory or object shapes further.
}

triggerTypeConfusion();

The real-world POC would be much more complicated, but this shows the idea: an attacker introduces an incompatible type, and if the browser doesn’t check properly, exploits memory unsafely.

Vendor Patch

Microsoft and Chromium rapidly patched CVE-2025-25000. You should ensure your Edge and Chrome browsers are fully up-to-date. Most users will get this update automatically, but check manually to be sure.

Open Edge.

2. Go to edge://settings/help.

Closing Thoughts

CVE-2025-25000 shows how serious browser vulnerabilities can be, and why browser security updates are crucial. Even the act of visiting a webpage can expose you to serious risk if your browser isn’t patched. If you’re a defender, push patches quickly, monitor for exploit attempts, and educate users.

Stay safe out there — and patch your Edge!

By [Your Name], Security Enthusiast
*(Exclusive for this post, simplified and practical for all readers.)*

Timeline

Published on: 04/04/2025 01:15:38 UTC
Last modified on: 04/23/2025 15:53:52 UTC