On March 20, 2023 OpenAI temporarily took ChatGPT offline after discovering a bug in the open-source Redis client library redis-py. The flaw allowed a corrupted connection in the Redis Cluster cache to return data belonging to a different user, exposing titles from another active user's chat history and, in a limited set of cases, payment details of approximately 1.2% of ChatGPT Plus subscribers. Exposed information could include first and last name, email address, payment address, credit card type, the last four digits of the card, and expiration date, though full card numbers were never revealed.

The issue arose when a request was cancelled after being queued but before a response was dequeued, causing the connection to retain residual data. OpenAI patched the library, added redundant data checks, improved logging, and reinforced the Redis cluster to prevent similar incidents. The incident underscores the critical role of open-source components in large‑scale AI services, the importance of rigorous testing under asynchronous workloads, and the heightened scrutiny on data privacy and trust in AI platforms.