Period tracker Stardust shares users' health data with analytics firm, Mozilla finds
Research reveals Stardust transmits sensitive reproductive health data to third parties.
1Privacy claims under scrutiny
While Stardust claims user data remains private, Mozilla's investigation found the app shares sensitive health information including birth control methods, reproductive goals, and symptoms with analytics firm RudderStack. This data is tied to unique identifiers instead of names.
2Non-anonymous data
As the FTC has long warned, replacing names with IDs doesn't anonymize data. Mozilla security researcher Shoshana Wodinsky used network traffic analysis to identify Stardust as the only app among six tested that shared such data with third parties.
3False encryption claims
Stardust claimed end-to-end encryption in 2022, but TechCrunch's network analysis proved otherwise. The app had previously raised privacy concerns when downloads surged after the US abortion rights reversal.
4Legal request risks
As US-based companies, both Stardust and RudderStack remain subject to law enforcement data requests. While Stardust states RudderStack is contractually prohibited from misusing data, inherent risks of data sharing persist.
5Recommended alternative
Mozilla endorsed Euki as 'squeaky clean' among tested apps, noting it doesn't share data with third parties through core features and keeps health data device-local.
6Health app privacy warning
This research highlights the need for caution regarding health data security. Users should be aware apps may share data invisibly in the background, with risks including breaches, security flaws, and legal demands always present.