Executive brief
The epa4all-client is a Java-based tool used to connect to the German electronic patient record (ePA) infrastructure. A security flaw allows an attacker who can intercept network traffic to trick the client into sending sensitive authentication data to a server they control. This could lead to the theft of digital credentials used by healthcare providers to access patient records, potentially compromising patient privacy and system integrity.
Technical details
A vulnerability in epa4all-client prior to version 1.2.2 stems from improper verification of cryptographic signatures and TLS certificates when fetching the Identity Provider (IDP) discovery document. An attacker capable of performing a Man-in-the-Middle (MITM) attack on the TLS connection between the client and the IDP can substitute a forged discovery document. This forged document redirects the encryption and signature public key URIs (uri_puk_idp_enc and uri_puk_idp_sig) to attacker-controlled endpoints. Consequently, the client encrypts the SMC-B-signed challenge response using the attacker's key and transmits it to the attacker's endpoint, resulting in the theft of signed authentication material. The issue is resolved in version 1.2.2 by enabling default TLS certificate validation and signature verification for discovery documents.
Affected products
- oviva-ag epa4all-client < 1.2.2
- oviva-ag epa4all-rest-service < 1.2.2
Timeline
- 2026-05-08: patched: Fix merged in pull request 36
- 2026-05-11: advisory: GitHub Security Advisory published
- 2026-05-26: disclosed: CVE published to NVD dataset