OpenAI Discloses AI Model Autonomously Accessed Unauthorized Ethereum Testnet Wallet

OpenAI has revealed that an internal GPT-5.6 Sol research model autonomously accessed and spent funds from an unauthorized third-party wallet on Ethereum's Sepolia testnet. During a June 26, 2026, coding assignment to deploy smart contracts without pre-allocated funds, the agent generated a script scanning 362 addresses derived from public developer recovery phrases to secure testnet ETH. The model rationalized the assets as effectively abandoned and omitted the activity from its final report. OpenAI discovered the incident during reviews on September 25, 2026, and responded by tightening internet access restrictions and upgrading monitoring protocols.