Observed Signal · Jul 16, 2026 · Research Findings · Source: techcrunch · Impact: 3/5 · Sentiment: Negative
Privacy Market: Stardust shares users' health data with RudderStack
Mozilla research found that period-tracking app Stardust shared sensitive users' health information with third-party analytics company RudderStack. The shared fields reportedly included birthdate, birth control type, reproductive goals, and specific symptoms, and records were tied to a persistent unique identifier rather than a name. Mozilla tested six period-tracking apps and found Stardust was the only one sharing sensitive health details with another company. RudderStack is said to be contractually prohibited from selling or using the data for its own purposes, but both U.S.-based companies can still receive law enforcement demands. TechCrunch previously reported in 2022 that Stardust's claim of end-to-end encryption was false after network-traffic analysis. Mozilla recommended Euki as an app that did not share health data off-device.
Research exposes real-world data-sharing of sensitive health information with analytics vendors, highlighting privacy, compliance, and law-enforcement risk implications for consumer apps and data intermediaries.
Key Takeaways & Evidence Grounding
- Mozilla's research found Stardust shared users' sensitive health information with third-party analytics company RudderStack.
- Shared data reportedly included birthdate, birth control type, reproductive goals, and specific symptoms, tied to a unique identifier.
- Mozilla tested six period-tracking apps and found Stardust was the only one sharing sensitive health data with another company.
- A Stardust spokesperson said RudderStack is contractually prohibited from selling or using the data for its own purposes.
- TechCrunch previously found in 2022 that Stardust's claim of end-to-end encryption was false after analyzing the app's network traffic.
Connected Companies & Entities
5 Entities mappedBBC
Public-service broadcaster with global digital publishing and streaming operations.
“As quoted by BBC News, a Stardust spokesperson said that RudderStack is “contractually prohibited from selling or using it for its own purpo...”
FTC
US regulator for consumer protection and competition enforcement.
“(The FTC has long warned that this does not make the data anonymous or prevent it from being linked back to a person.)...”
Mozilla
Privacy software and web media products under non-profit ownership.
“As new research by Mozilla discovered, some users might find that claim to be a stretch....”
RudderStack
Warehouse-native customer data platform for collection, identity and activation.
“Stardust was found to be sharing users’ sensitive health information with third-party analytics company RudderStack....”
TechCrunch
Technology publisher monetising audience, events and branded campaigns.
“TechCrunch previously wrote about Stardust in 2022 after the app surged in downloads following the overturning of the constitutional right t...”
Ontology Mapping & Concepts
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