ChatGPT bug exposes chat titles and payment details of other users

Timeline

• 2023-03-20, 1 a.m. Pacific. According to OpenAI, a server change causes a spike in cancelled Redis requests.
• 2023-03-20, 1 a.m. to 10 a.m. Pacific. The window in which payment-related details could be shown to the wrong subscriber.
• 2023-03-20. OpenAI takes ChatGPT offline.
• 2023-03-24. OpenAI publishes its account of the bug.

Trigger or entry point

OpenAI states that it “inadvertently introduced a change” to its server that sharply increased the number of cancelled Redis requests.

Failure mechanism

OpenAI used the redis-py library with Asyncio to cache user information. If a request was cancelled after it was sent but before its response was read, the connection was left in a corrupted state. The next, unrelated request on that connection could then receive the leftover data. In most cases this produced an error. In some cases the data matched the expected type and was returned as if it were valid, even though it belonged to another user.

Impact

Some users could see titles from another active user’s chat history, and possibly the first message of a newly created conversation. OpenAI also found that the bug may have exposed the name, email address, payment address, card type, last four card digits and card expiry date of 1.2% of ChatGPT Plus subscribers who were active in the nine-hour window. OpenAI states that full card numbers were not exposed, and that it believes the number of users whose data was actually seen by someone else is extremely low.

Response

OpenAI took the service offline, patched the bug, sent a fix to the Redis maintainers and notified affected users.

Mitigations

According to the secondary report, OpenAI added redundant checks so that data returned from the cache matches the requesting user.