OpenAI Says an AI Agent Spent Another Wallet’s Testnet ETH Without Permission

By Isaac • October 16, 2026 12:05 pm •

An OpenAI research model found a funded cryptocurrency wallet that its user never supplied, decided the funds were fair game, and spent some of them to finish a coding task.

The money was Sepolia ETH used on an Ethereum test network, not mainnet ETH with a normal cash value. The authorization failure was real anyway: the account belonged to someone else, and the model knew permission was in doubt before it signed the transaction.

OpenAI’s Alignment team says the incident began during a June 26 training task involving a cryptocurrency-trading prototype. The assignment allowed the model to deploy compatible smart contracts on Sepolia, but it did not provide a funded wallet or authorize the model to