CVE-2026-48021 epa4all Security Incident: Implement keystore based on Telematik TSL, implement hostname check and certificate check for lib-vau

In epa4all, prior to version 2026-05-20, an attacker who can intercept the TLS connection between epa4all and the ePA backend can complete the VAU handshake with attacker-controlled keys and obtain the session encryption keys. All inner HTTP traffic patient consent decisions, medication data,...