epa4all-client vulnerabilities

The epa4all-client library (Java Client for epa4all / ePA 3.0 in Telematik Infrastruktur) prior to version 1.2.2 does not properly validate TLS certificates. An attacker on the network path between the ePA service and the Konnektor can present any TLS certificate (self-signed, expired, wrong CN) and intercept all SOAP traffic, including patient identifiers (KVNR), SMC-B card operations, document content, and credential exchanges.

In the epa4all-client Java client, the SignedPublicKeysTrustValidatorImpl.isTrusted() method discards the boolean return value of ECDSA signature verification, always returning true for any structurally valid signature.

epa4all-client version 1.2.4 and earlier allows any network-reachable caller to write arbitrary documents to any patient's electronic health record using the institution's SMC-B card. In a misconfigured deployment (e.g., following the Docker example in the README), this is exploitable from the local network without credentials.

In the epa4all-client Java client, a MITM attacker on the TLS connection between client and IDP can substitute a forged discovery document, redirecting the client to attacker-controlled URLs. The client then encrypts the SMC-B signed challenge response with the attacker's key and sends it to the attacker.