Two-thirds of test digital vaccination applications exhibit behavior that may put users’ privacy at risk. The risks are substantial as these apps are required for large populations worldwide, allowing hackers an extensive target base. Digital passports apps store proof of a person’s COVID-19 vaccination status, full name, date of birth, and other personally identifiable information (PII) encoded in a QR code or displayed directly in the app. The issuer of the apps are typically the health and IT departments of governments, while the developers are often contracted experts in mobile software development.”]