A bug in Safari 15 can leak your browsing activity, and can also reveal some of the personal information attached to your Google account, according to findings from FingerprintJS, a browser fingerprinting and fraud detection service (via 9to5Mac). The vulnerability stems from an issue with Apple’s implementation of IndexedDB, an application programming interface (API) that stores data on your browser.
As explained by FingerprintJS, IndexedDB abides by the same-origin policy, which restricts one origin from interacting with data that was collected on other origins — essentially, only the website that generates data can access it. For example, if you open your email account in one tab and then open a malicious webpage in another, the same-origin policy prevents the malicious page from viewing and meddling with your email.