Security researchers have uncovered a vulnerability in one of the most popular AI tools for spreadsheets. ChatGPT for Google Sheets can be tricked into shipping sensitive corporate data to attackers with nothing more than a single poisoned cell. The flaw, laid out in detail by PromptArmor on May 27, 2026, shows how indirect prompt injection in a single sheet triggers scripts that pull workbooks from across a victim’s Google account. No approval clicks required. Even the “stop” button in the sidebar fails to halt the process. Consider a finance analyst reviewing quarterly numbers. She imports a CSV from a vendor. That file contains hidden instructions, rendered in white text so they stay invisible. Later she asks the add-on a routine question about integrating the new data. The model, now carrying the injected commands in its context, quietly launches an external script. Within moments her financial model, linked reports, and a dozen other spreadsheets start streaming to an attacker-controlled server.…