https://www.bleepingcomputer.com/news/security/threema-claims-encryption-flaws-never-had-a-real-world-impact/

A team of researchers from ETH Zurich has published a paper describing multiple security flaws in Threema, a secure end-to-end encrypted communications app.

Threema is a privacy-focused and security-enhanced Swiss-made communications app used by the country's government, army services, and over 10 million users and 7,000 organizations worldwide.