CyLab Study Finds 'Privacy-Preserving' Tracking Alternatives May Still Expose Users
By Michael Cunningham
As major technology companies race to replace traditional online tracking tools with systems marketed as more privacy-conscious, new CyLab research suggests that some of those alternatives may offer far less protection than advertised.
In a recent study, researchers found that privacy systems built around grouping users by broad behavioral topics rather than individual identifiers can still leave people surprisingly vulnerable to re-identification when modern artificial intelligence models analyze behavior over time.
The findings, detailed in "Sequential Pattern Recognition Attacks Against Deployed Topic-Based Mechanisms," raise broader concerns about whether many emerging privacy-preserving technologies are truly safeguarding users, or simply repackaging surveillance in a less obvious form.
Saranya Vijayakumar, a Ph.D. candidate in Carnegie Mellon's Computer Science Department and the paper's lead author, presented the work at the 12th International Conference on Information Systems Security (ICISSP 2026) in Marbella, Spain, where it received the ICISSP 2026 Best Student Paper Award. The research team also included S3D faculty members Norman Sadeh and Matt Fredrikson.
The research focused on systems like Google's now-deprecated Topics API, which was designed as a replacement for third-party cookies. Instead of assigning users a persistent ID that advertisers could track across websites, Topics categorized users based on general interests, such as cooking, sports or news, with the goal of obscuring individual identity within larger groups.
But Vijayakumar said that premise begins to unravel when user behavior is analyzed across multiple points in time.
"The broader takeaway is that when you're looking at something temporally, the privacy-preserving nature can change a lot," Vijayakumar said. "If you have multiple epochs of data, you have to examine something thinking of yourself as an advertiser who can collect data over time."
Read the full story on the CyLab website.