CVE-2026-50577

Name of the Vulnerable Software and Affected Versions ePA 3.x Integration versions prior to 1.3.0

Description The software fails to update the request counter in the app/vau/VAUProtokoll.py file when constructing VAU messages. This results in the server reusing AES-GCM nonce and key combinations across responses. A network attacker can collect repeated ciphertexts to recover the XOR of plaintexts and use predictable inner HTTP headers and JSON fields to access sensitive patient health records. Additionally, the reuse of nonces allows for the recovery of the GHASH authentication key via the Joux forbidden attack, enabling the forgery of AES-GCM messages and the injection of malicious responses. The system also fails to maintain the last response counter, which weakens replay and ordering validation.

Recommendations Update ePA 3.x Integration to version 1.3.0.