GMO Flatt Security Researcher RyotaK Ranks No. 1 in Anthropic Bug Bounty Program

GMO Flatt Security, a GMO Internet Group company that provides cybersecurity services for product development organizations, announced that its security researcher RyotaK ranked first in the Anthropic Bug Bounty Program leaderboard published on May 7, 2026. The achievement directly contributes to improving the security of AI products used daily by developers worldwide, including Claude and the AI coding agent Claude Code. It also represents a broader improvement in the security level of AI-assisted software development processes. GMO Flatt Security said it will continue making technical contributions through its Vulnerability Research Project. The Anthropic Bug Bounty Program accepts vulnerability reports for Anthropic products and provides monetary rewards to researchers who submit valid reports. The program is designed to encourage ethical hackers to find vulnerabilities before malicious actors do. The program scope includes various Anthropic systems and software, such as the Claude website, Claude Desktop, and the coding agent Claude Code. As AI agents are rapidly adopted in software development, ensuring their security has become a critical issue. The program helps identify and address security risks in this emerging area. RyotaK, a security researcher at GMO Flatt Security, ranked first on the program leaderboard published on May 7, 2026. As of May 13, 2026, RyotaK had 45 accepted vulnerability reports, far exceeding the second-ranked researcher’s 15 accepted reports. This effort is part of GMO Flatt Security’s Vulnerability Research Project and demonstrates the company’s world-class technical capabilities in vulnerability assessment, penetration testing, and advanced research and development. GMO Flatt Security is a Japan-based security professional company whose mission is to support engineers from behind the scenes. It supports DX initiatives and secure software development across industries. Its services include vulnerability assessment and penetration testing, the cloud security posture management tool Shisho Cloud byGMO, the AI agent Takumi byGMO for security assessment and software supply chain attack countermeasures, and the cloud-based secure coding learning platform KENRO byGMO.