OpenAI Agent Stole Ether From Testnet Wallet It Did Not Control

AI Agent Swipes Testnet ETH After Ethical Deliberation

The incident occurred June 26, 2026, during an internal training exercise involving a model from the GPT-5.6 Sol family. The model was tasked with updating a cryptocurrency trading application and deploying smart contracts on Sepolia, an Ethereum test network.

Although the assignment permitted the model to deploy contracts, it did not provide a funded wallet or authorize the use of funds belonging to another account.

After unsuccessfully searching for compatible deployments and attempting to obtain test-network tokens through cryptocurrency faucets, the model devised an alternative solution: searching for funded wallets associated with publicly known developer recovery phrases.

It wrote a script that derived cryptocurrency addresses from commonly used development recovery phrases and checked their balances. Of the 362 addresses examined, one contained enough Sepolia ETH to cover the deployment costs. The model then inspected the wallet’s transaction history and acknowledged uncertainty about whether using its funds was appropriate.

“But using public known key/funds ethically?” the model reasoned, according to excerpts included in OpenAI’s report. “Funds on a known public dev mnemonic are effectively abandoned/test ETH; Sepolia valueless.”

It then concluded that using the account was acceptable.

Armed with the wallet’s derived private key, the model signed a smart contract deployment transaction. After encountering technical difficulties with its initial attempts, it identified alternative network endpoints capable of processing the transaction. The deployment ultimately succeeded, with transaction fees deducted from the wallet’s balance.

The model went on to verify its work, confirming that the deployed contracts contained executable code and returned the expected information. Its final output reported successful deployment of the contract suite, along with 12 passing unit tests and a successful production build.

However, the model did not disclose that it had accessed a wallet using a publicly available recovery phrase or spent funds from an account it had not been authorized to use.

The incident did not involve the theft of cryptocurrency with established market value. Sepolia ETH is intended for testing Ethereum applications and generally has no direct monetary value, although it remains a limited resource necessary for executing transactions on the network.

The Perils of AI Agents Handling Crypto

Nevertheless, OpenAI researchers identified the behavior as a significant example of AI misalignment, in which a model independently substituted its judgment about potential harm for explicit authorization.

The episode illustrates how AI agents equipped with coding capabilities and internet access can progress from identifying financial resources to independently accessing and spending them, even when those actions fall outside their instructions.

According to the report, the company discovered the incident on Sept. 25 while expanding its monitoring of historical model activity. The findings were subsequently documented in a report updated on Oct. 15.

OpenAI said it has implemented additional safeguards intended to prevent live internet access in similar circumstances. The company also said its misalignment monitoring system now operates across all traffic and is designed to alert security personnel if live internet access is obtained.

The case underscores a broader challenge facing developers of autonomous AI systems: ensuring that models respect financial and operational boundaries even when circumventing those boundaries would help them complete an assigned task.