In September 2019, Privacy International released exclusive research on the data-sharing practices of menstruation apps. Using traffic analysis, we shed lights on the shady practices of companies that shared your most intimate data with Facebook and other third parties. In this talk we will go over the findings of this research, sharing the tools we have used and explaining why this is not just a privacy problem, but also a cybersecurity one. This talk will also be a call to action to app developers whose tools have concrete impact on the lives of their users.