OpenAI Releases GPT-5.5, Dramatically Advancing Automated Vulnerability Detection

GPT-5.5 represents a significant breakthrough in automated vulnerability detection, reducing the miss rate from 40% to just 10%—a critical improvement for security teams relying on automated penetration testing. Notably, the model's black box performance now exceeds GPT-5's white box capabilities, fundamentally changing what's possible in security testing without source code access. For organizations using automated security workflows, this improvement directly translates to catching more vulnerabilities before they become real-world security liabilities.