Chrome Sandbox Security Flaw: Technical Analysis

A serious security flaw, CVE-2025-2783, has been found in Google Chrome, affecting the Mojo inter-process communication (IPC) system on Windows.

With a high CVSS score of 8.8, the issue comes from poor validation in how Chrome handles certain system resources. This lets attackers create harmful content that can escape Chrome’s security sandbox — usually by tricking users into clicking a phishing link or visiting a fake website.

The flaw was discovered during Operation ForumTroll, a targeted attack that hit Russian media, education, and government networks.

This zero-day exploit allowed hackers to run commands outside of Chrome, gain long-term access, move across networks, and install malware on the victim’s system.

Rapid Response and Patch Analysis: CVE-2025-2783

Google responded quickly to a serious Chrome vulnerability, CVE-2025-2783, reported by Kaspersky researchers Boris Larin and Igor Kuznetsov on March 25, 2025. A fix was released just five days later in Chrome version 134.0.6998.177.

Experts analyzed the patch using tools like Ghidra, IDA Free, and BinDiff. They compared the vulnerable version (134.0.6998.142) with the patched release and found major improvements. These include better input checks to block invalid Mojo handles, new safety conditions to prevent sandbox escapes, and early exits in code to stop unexpected message types.

The patch also added stronger filtering for incoming messages, better crash prevention, and detailed logging to help catch misuse. Chromium Git logs show further updates like rejecting suspicious Mojo data and securing renderer processes.

This vulnerability was especially dangerous because it allowed attackers to break out of Chrome’s sandbox and run malicious code on a user’s system—just from visiting a harmful site.

Google has pushed the fix via Chrome’s auto-updater. Still, users and organizations should stay alert.
Make sure Chrome updates are enabled, block risky domains through DNS or firewalls, and train users to recognize phishing attempts.

To detect attacks like this, security tools should watch for unusual Chrome activity, such as unexpected child processes. Memory-focused EDR solutions can also help spot exploitation attempts.

Since CVE-2025-2783 was used in real attacks, it highlights how advanced threat actors have become and why strong security practices matter.