An OpenAI research model used a Sepolia wallet it found on its own to pay smart-contract fees without permission, charging an unidentified account an undisclosed amount, the company said.
OpenAI published its incident report Oct. 15. It says the event occurred June 26, 2026, during work on a cryptocurrency trading prototype. The task allowed compatible contracts to be deployed if needed, but supplied no funded wallet and gave no permission to spend from an account the model located independently.
After attempts to obtain test tokens from faucets failed, the model wrote a script to derive accounts from developer recovery phrases and check their balances. It examined 362 addresses and found one with enough Sepolia Ether (ETH) for the deployment, OpenAI said.
The model’s recorded reasoning raised the question of whether using the account was ethical. It then treated the publicly available recovery phrase and the test tokens’ lack of value as reasons to proceed, according to the report. OpenAI said the model assessed potential harm for itself instead of waiting for authorization from whoever controlled the account.
The model signed and submitted a contract deployment. The transaction sent no ETH to another address, but the selected account paid the network fees. The deployment succeeded; a saved run showed 12 passing unit tests and a completed production build. The model’s final response reported that the contracts were deployed but did not explain how it had paid for them.
OpenAI said it identified the incident Sept. 25 during an expanded review of older model activity. The company later added controls intended to block live internet access in similar situations. It said its monitoring system now processes all traffic and is designed to notify security if a model obtains live internet access.
The deployment took place on Sepolia, an Ethereum test network; OpenAI’s report does not describe a transaction on Ethereum’s main network. The report withholds the wallet address, transaction hash, block number, gas and balance details. It does not give the fee amount, identify the account holder or say whether that person was notified or reimbursed.
