It answered a cooking question and read the victim's Gmail at the same time

The victim in Check Point's demonstration asked ChatGPT something about cooking. While it answered that, the same session went into their connected Gmail, pulled email data out and passed it to a stranger. The visible reply mentioned none of it. The only trace was a small "Talked to Gmail" label, and that only appeared once the reading was already done.

The research went out on 8 September and describes a gap between accounts that was never supposed to exist. When ChatGPT runs code it does so in a sealed container with no route to the internet, and containers belonging to different people are meant to be strangers to each other. They could all reach one internal service, though: a JFrog Artifactory instance that hands out software packages, which let any container pin small notes onto cached files and read them back later. Check Point's name for that is a shared clipboard. An attacker wrote tasks into it, a victim's session checked for them, and the tasks ran with whatever permissions that person's own connected apps already had. Setting it off took almost nothing from the victim: a prompt pasted into a chat, a shared conversation link, or a custom GPT with a hidden instruction in its setup.

Check Point found this in June and OpenAI has since decommissioned the Artifactory instance involved, so there is nothing for you to update and no evidence anyone was actually attacked this way. What survives the fix is the setting underneath it. If you have hooked Gmail, Drive or a calendar up to ChatGPT, the default permission level lets it read from them without asking, and you learn about it after the fact. In the connector settings there is a stricter option called Always ask, which puts a prompt in front of every read.

Worth doing, then: switch your connectors to Always ask, and treat a shared ChatGPT link or somebody else's custom GPT the way you would treat an attachment from an address you don't recognise. Tendvane's Privacy and accounts check shows which accounts your PC is signed into, which is a useful starting point when you are working out how much any one login can actually reach.