Security vulnerabilities hit every browser, but not all get headlines. CVE-2022-3655 is one such flaw found in Google Chrome’s Media Galleries feature, quietly patched before Chrome version 107..5304.62. This post dives deep into how a heap buffer overflow could let attackers crack open Chrome, what makes this bug unique, and how it could possibly be exploited—with code snippets and resource links to dig further.

What is CVE-2022-3655?

CVE-2022-3655 is a _heap buffer overflow_ vulnerability in Google Chrome’s Media Galleries. It allowed an attacker—who could trick you into installing a malicious extension—to exploit heap memory corruption. By leading you to a specially crafted HTML page, the attacker could exploit Chrome’s internal memory handling, possibly leading to arbitrary code execution or at the very least, a browser crash.

Affected versions: Google Chrome prior to 107..5304.62

- Severity: Medium (Chromium Security Severity Guidelines)

Original Reference

- CVE Details
- Chromium bug tracker (Issue 1376181)
- Official Chrome Releases Blog

How It Happened

Background:  
Media Galleries in Chrome let extensions access user media like photos and videos, with user permission. It’s powerful—but risky if mismanaged.

The Problem:  
The Chrome code handling file access didn’t properly check buffer boundaries when processing certain data from media gallery files. If a Chrome extension passed larger-than-expected data from a crafty HTML page back to the Media Galleries API, the browser could write or read past the end of an allocated buffer—classic “heap buffer overflow.”

Why It’s Dangerous:  
Such overflows can be turned into _heap corruption_. Skilled attackers might craft malicious inputs that, under the right conditions, change what gets executed—possibly running arbitrary code or injecting malicious actions.

Sample Attack Flow

1. Attacker writes a malicious extension and submits to Chrome Web Store (or convinces you to load it as a developer extension).
2. Malicious extension opens a crafted HTML page (could be on the web or bundled with the extension).
3. The page interacts with the Media Galleries API and sends purposely malformed or oversized data to Chrome’s internal code.
4. Heap buffer overflow is triggered due to lack of proper boundaries in Chrome’s Media Galleries memory processing.
5. Heap corruption occurs, which could lead to crashing the browser, leaking sensitive data, or (in rare cases) executing arbitrary code.

Proof of Concept (Simplified)

Here’s a _simulated_ pseudo-code snippet representing how such a bug could work. (Actual Chrome internals are in C++, but this gives you the idea.)

// Malicious Chrome extension content script

// Assume 'mediaGalleryApi' is available to extensions
const exploitPayload = new Uint8Array(x10000); // Very large buffer

// Fill buffer with crafted data
for (let i = ; i < exploitPayload.length; i++) {
    exploitPayload[i] = x41; // Fill with 'A's (x41)
}

// Pass the large payload to the vulnerable API
mediaGalleryApi.processMedia(exploitPayload.buffer);

// Normally, inside Chrome, the code would look something like:
void processMedia(const uint8_t* data, size_t length) {
    uint8_t buffer[1024]; // fixed-size buffer: too small!
    memcpy(buffer, data, length); // <-- Here: no bounds check
    // Heap corruption could happen if length > 1024
}

In reality, the real exploit would use memory spraying and possibly further JS/C++ tricks—but this shows the unsafe pattern: copying unchecked data into a fixed-size buffer.

Mitigation and Patch

Google fixed this bug by properly checking the size of incoming data before copying into memory. They also plugged other similar unsafe code paths. To stay safe, just make sure you’re running Chrome 107..5304.62 or newer.

More Resources

- Chromium Security: Heap Overflow
- Safe Buffer Handling in C++
- Google Project Zero: Exploiting Heap Corruption

Bottom Line

CVE-2022-3655 is a text-book example of why even medium-severity vulnerabilities deserve attention. With the right social engineering, attackers can chain these bugs into something worse—so patching fast and staying careful with extensions is critical.

*Stay curious, stay patched, and don’t trust everything you install!*

Timeline

Published on: 11/01/2022 23:15:00 UTC
Last modified on: 11/10/2022 00:15:00 UTC