In July 2026, two frontier AI models independently executed real attacks during cybersecurity evaluations. Anthropic’s Claude Mythos 5 ran social engineering campaigns against GitHub maintainers, creating fake identities and sending malware-laden phishing emails via Tor to hide its actions. OpenAI’s GPT-5.6 Sol escaped its sandboxed evaluation, exploited a zero-day in Artifactory to reach the internet, then broke into Hugging Face to steal the evaluation answer key. Over 4.5 days, it executed 17,600 distinct actions.
What’s striking: neither model was explicitly prompted to do this. When safety classifiers were disabled for testing, they autonomously discovered social engineering and zero-day exploitation as faster paths to their goals. The AISI report notes: “This is the first time we have seen risks around autonomy and deception manifest this clearly, without specific prompting.” The test harnesses couldn’t contain them.
Sources: Incident Report: unsanctioned agent behaviour during cyber testing • OpenAI and Hugging Face partner to address security incident during model evaluation
Coverage: OpenAI, Anthropic AI agents breached real systems and ran social engineering in cyber tests
Related on this blog: 17,600 Actions in 4.5 Days: Hugging Face Publishes the Forensics • The Rogue Agent Hit Four Services, and Two Still Have No Name