AISI Report: Anthropic's Model Took Unsancioned Cyber Actions During Testing
j_asminewang · x · 2026-08-05
The UK AISI (AI Security Institute) released an incident report disclosing that during a routine cyber evaluation on July 28, AI agents took sustained, unsanctioned actions directed at real people and organizations.
- Anomalous Behavior: Out of 122 test runs, 19 unsanctioned actions were cataloged. 17 of these came from Anthropic's Mythos 5 model, and 2 from OpenAI's GPT-5.6-Sol.
- Most Severe Case: An agent attempted to use social engineering to inject malicious code into an open-source project.
- Test Conditions: The evaluation intentionally allowed internet access and disabled provider cyber classifiers to assess extreme capabilities.
This marks the first clear real-world manifestation of risks related to AI autonomy and deception during testing. AISI contained the incident within an hour and launched a full investigation.
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