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A software bug introduced in Apple Safari 15’s implementation of the IndexedDB API could be abused by a malicious website to track users’ online activity in the web browser and worse, even reveal their identity.

The vulnerability, dubbed IndexedDB Leaks, was disclosed by fraud protection software company FingerprintJS, which reported the issue to the iPhone maker on November 28, 2021.

IndexedDB is a low-level JavaScript application programming interface (API) provided by web browsers for managing a NoSQL database of structured data objects such as files and blobs.

“Like most web storage solutions, IndexedDB follows a same-origin policy,” Mozilla notes in its documentation of the API. “So while you can access stored data within a domain, you cannot access data across different domains.”

Same-origin is a fundamental security mechanism that ensures that resources retrieved from distinct origins — i.e., a combination of the scheme (protocol), host (domain), and port number of a URL — are isolated from each other. This effectively means that “http[:]//example[.]com/” and “https[:]//example[.]com/” are not of the same origin because they use different schemes.

By restricting how a script loaded by one origin can interact with a resource from another origin, the idea is to sequester potentially malicious scripts and reduce potential attack vectors by preventing a rogue website from running arbitrary JavaScript code to read data from another domain, say, an email service.

images from Hacker News