Google researchers discovered a feature with multiple bugs in Safari that allowed advertisers to track users online using iOS and Mac OS Safari.
Intelligent Tracking Prevention (ITP) included in Safari on iOS and iPadOS 13.3, Safari 13.0.4 on macOS Catalina, Mojave, and High Sierra.
The function that had to block online trackers in Safari allowed advertisers to track users online using a technique known as Fingerprinting. The Financial Times has looked into an investigation that reported this problem.
The problem was in multiple security holes, more details in Google’s research. The vulnerabilities were in functionality within Safari itself.
The security holes in Safari were reported to Apple as early as August 2019. Apple then fixed and closed the security holes in December 2019. There has been no correspondence about the security holes, as this is very common in security-related problems on a width scale.