GPT‑6 Cyber vs. Claude Sonnet 5.5

GPT-6 Cyber is a frontier AI cybersecurity model developed by OpenAI to support autonomous vulnerability research, exploit validation, secure software development, and advanced security testing. The model is specifically trained to investigate complex software environments, discover exploitable vulnerabilities, and help security professionals develop effective remediation strategies. Its capabilities include source code analysis, reverse engineering, vulnerability reproduction, exploit development, and investigation of security weaknesses across large software projects. GPT-6 Cyber can conduct extended security research workflows that involve identifying potential attack paths, testing hypotheses, validating technical findings, and producing reproducible evidence for security teams. During OpenAI's research campaigns, the model identified 81 previously unknown high-severity Firefox vulnerabilities and helped develop candidate patches for affected components. It also reproduced 1,724 Linux kernel vulnerabilities and generated working exploits for 948 of them, demonstrating its ability to validate security issues at scale. On the ExploitGym benchmark, GPT-6 Cyber achieved a 48.5% success rate compared with 32.1% for GPT-5.6 Cyber, while achieving 40.3% vulnerability recall in an internal web penetration testing evaluation. The model incorporates specialized alignment training to follow authorized testing scopes, respect security restrictions, and avoid exploiting systems that fall outside the researcher's stated objectives. In OpenAI's ExploitGym Honeypot evaluation, GPT-6 Cyber avoided attacking out-of-scope services in 99.93% of tests without deployment safety instructions and 100% of tests when those instructions were included. Its deployment safeguards include misalignment monitoring, misuse detection, IP allowlisting for API access, human oversight recommendations, and additional protections for operational technology and critical infrastructure systems.

Claude Sonnet 5.5 is Anthropic’s faster, lower-cost Claude 5.5 model for well-scoped professional work, software development, agentic workflows, and content creation. Anthropic positions it below Claude Opus 5.5 for the most complex open-ended work, but says it can perform comparably on some benchmarks when run at higher effort settings. The model delivers a particularly large improvement in coding, including a 70.6% result on Terminal-Bench 4.0, 46.2% on FrontierCode at Max effort, and 55.5% on CursorBench 4.0. It also scores 1844 on GDPval-AA, 1811 on AA-Briefcase, 64.5% on Humanity’s Last Exam with tools, and 80.1% on OSWorld 2.1 partial. Anthropic reports that Sonnet 5.5 is better at long-horizon work, image understanding, collaboration, and codebase comprehension than Sonnet 5. The company also highlights design-oriented improvements, including the ability to produce polished documents, spreadsheets, slides, and user interfaces with less editing. Sonnet 5.5 generates output more than 30% faster than its predecessor and is Anthropic’s fastest Sonnet model to date. Although its listed token prices are unchanged from Sonnet 5, Anthropic says greater token efficiency can reduce per-task cost by up to 30%. Pricing is $2 per million input tokens, $10 per million output tokens, $2.50 per million cache-write tokens, and $0.20 per million cache-read tokens. The model includes cyber safeguards, biology safeguards, reasoning-extraction protections, and preserved-thinking controls, with some higher-risk cyber requests falling back to Sonnet 5. Claude Sonnet 5.5 is available with zero data retention across Claude products, the Claude Platform, AWS, Google Cloud, and Microsoft Azure under the model name claude-sonnet-5-5.