OpenAI says new GPT-5.5-Cyber outperforms Anthropic's Mythos on cybersecurity benchmark

OpenAI released the full GPT-5.5-Cyber model, which sets new highs on cybersecurity benchmarks and outperforms Anthropic's Mythos. An updated Codex Security plugin now covers the full pipeline from discovery to patch generation. OpenAI also launched a partner network of over 25 security firms and an open-source patching initiative.