Google has established a new milestone in cybersecurity research by awarding a security researcher known as “Micky” a record-breaking $250,000 bug bounty for discovering a critical vulnerability in Chrome browser. This payment represents the maximum possible reward for sandbox escape vulnerabilities, highlighting the severity and sophistication of the security flaw discovered.
Understanding CVE-2025-4609: A Complex Logic Bug
The vulnerability, designated as CVE-2025-4609, was identified by the researcher in April 2025 and affects the ipcz Mojo library, a crucial component responsible for managing inter-process communication within Chrome’s architecture. Google’s security team classified this flaw as high severity and described it as a “highly complex logic bug.”
What made this discovery particularly valuable was not just the vulnerability itself, but the comprehensive nature of the researcher’s submission. The report included detailed technical analysis, thorough documentation, and most importantly, a working proof-of-concept exploit demonstrating successful sandbox bypass capabilities.
Technical Analysis: How the Exploit Works
The proof-of-concept developed by Micky demonstrated an impressive 70-80% success rate in bypassing Chrome’s sandbox protection mechanisms. The exploit leverages manipulation of Chrome’s internal processes, specifically targeting the ability to duplicate parent browser processes for malicious code execution.
To illustrate the vulnerability’s impact, the researcher demonstrated arbitrary code execution by launching the system calculator application. This seemingly simple demonstration effectively proved that an attacker could execute any command on a victim’s system, completely circumventing Chrome’s security barriers.
From an attack vector perspective, exploitation requires minimal user interaction. An attacker would only need to direct a victim to a specially crafted website while using a vulnerable version of Chrome, making this a particularly dangerous threat for end users.
Rapid Response and Patch Deployment
Google’s security team demonstrated exceptional response time in addressing this critical vulnerability. The flaw was patched by mid-May 2025 with the release of Chrome version 136, approximately one month after initial discovery. The fix was also propagated to other Chromium-based browsers, including Microsoft Edge, Opera, Vivaldi, and Brave.
Maximum Bounty Criteria and Requirements
The $250,000 payout represents Google’s maximum reward tier for sandbox escape vulnerabilities. To qualify for this top-tier compensation, researchers must meet stringent criteria: submissions must demonstrate exceptional technical quality and must include working remote code execution capabilities. The comprehensive nature of Micky’s report, combined with the reliable exploit demonstration, justified this maximum payout.
Historical Context in Bug Bounty Programs
While Micky’s reward ranks among Google’s highest individual payouts, it falls short of the all-time record. That distinction belongs to researcher “gzobqq,” who received $605,000 in 2022 for discovering a chain of five critical vulnerabilities in Android’s operating system.
These substantial rewards reflect Google’s commitment to proactive security through crowdsourced vulnerability research. Bug bounty programs have proven invaluable for identifying sophisticated threats that might otherwise remain undetected until exploited maliciously.
This case exemplifies the critical importance of collaborative cybersecurity efforts between technology companies and independent security researchers. Regular browser updates remain essential for user protection, as they often contain fixes for vulnerabilities that could compromise system security. Users should prioritize keeping their browsers updated to the latest versions to maintain optimal protection against emerging threats.
