CVE-2025-0762 - How “Use After Free” in Google Chrome DevTools Prior to v132..6834.159 Risks Your Security

There’s a new Chrome bug on the block: CVE-2025-0762. And even though it’s somewhat under the radar, it could let hackers mess with your browser — especially if you use third-party Chrome extensions. Let’s break down what this bug is, how it works, and how someone might exploit it. No fluff, just the facts anyone can understand.

Vulnerability Type: Use After Free (UAF)

- Component Affected: DevTools (the panel you use for inspecting HTML/CSS, debugging, etc.)

Official Sources

- Google’s Security Blog Acknowledgement
- Chromium Issue Tracker (Reference)

What’s a “Use After Free,” Really?

Imagine you’re writing a note, and throw away the paper after finishing. Then, for some reason, you try writing on the *same* piece of paper you just tossed in the recycle bin. Sounds silly, right? That’s basically what a “Use After Free” bug is in the world of computers.

Technically, the program frees up a chunk of memory (RAM), but then tries using it again. If an attacker can predict exactly when that happens, they can sneak in and use that memory for something malicious — like code that takes over your browser.

You install a Chrome extension (with sketchy code or one that’s been compromised).

2. You use DevTools (like most web developers/debuggers do).

The extension abuses a bug in DevTools — it tricks Chrome into freeing up a chunk of memory.

4. The extension *quickly* reuses that same memory space — but with its own “booby-trapped” data on the heap.
5. Chrome DevTools, expecting the old data, uses the new, attacker-controlled data instead. Boom: heap corruption.

Visualized in Real Life

DevTools: "Hey, I’m done with this object. I'll free the memory."
Extension: (quickly!) "I'll fill that memory with MY evil code!"
DevTools: "Wait, I need that object again..." -- but now it’s not the original data.
Result: Unpredictable behavior. Possible browser compromise.

Code Example: A Simplified UAF Pattern

While the actual Chrome source is complex, here's a simple C++-like illustration of a “use after free”.

Object* obj = new Object();
delete obj;
if (someCondition) {
    // BAD! The object memory is already freed. Someone else could have overwritten it!
    obj->doSomething(); // Use after free occurs here
}

In Chrome’s case, the “object” is managed by DevTools (inside the browser), but Chrome extensions can interfere with the object’s lifecycle, triggering this bug.

How Could a Chrome Extension Pull This Off?

1. Leverage permissions: All Chrome extensions run in a privileged context. If you allow an extension to access DevTools, it can interact with those internals.
2. Force the bug: The extension sends a sequence of commands, or malformed data via the DevTools protocol, to force Chrome to delete (free) an object.
3. Race the browser: If timed right, the extension can get Chrome to use the freed object memory, but now it actually belongs to the extension’s code/data.
4. Corrupt the heap: Results range from crashing the browser (DoS) to executing code (potential privilege escalation).

Update Chrome: Always keep Chrome up to date. Versions before 132..6834.159 are at risk.

- Go to chrome://settings/help to check for updates.

Be wary of Chrome extensions: Only install trusted extensions with good reviews.

- Don’t use DevTools when unsure about extensions: If you’re debugging sensitive code, disable third-party extensions temporarily.

For Developers

- Audit your code for UAF bugs — they’re among the most serious and sneaky in C++ codebases like Chromium.
- Sanitize and validate user/client input rigorously in extension code.

References and More Reading

- Chromium Bug Trackers on UAF issues
- Detailed “Heap Corruption” Explained (OWASP)
- Chrome Extensions Security

Conclusion

CVE-2025-0762 is a silent, real threat — especially if you use Chrome extensions or DevTools. Attackers no longer need to trick you into visiting a site; a malicious extension can get the job done. Always keep Chrome current, use trusted extensions, and realize even “medium” bugs are worth taking seriously.

Stay safe, and happy (secure) browsing!

*This post is a simplified explanation with exclusive, easy-to-read context. For the latest details, always consult the official Chrome and Chromium blogs linked above.*

Timeline

Published on: 01/29/2025 11:15:09 UTC
Last modified on: 01/29/2025 15:15:17 UTC