VAU server authentication bypass in epa4all (CVE-2026-48021)

The VAU protocol client in epa4all does not verify the server's ES256 signature, certificate chain to the TI PKI root, OCSP revocation status, or role OID during the VAU handshake, despite deserializing the relevant fields. An attacker positioned on the network path between epa4all and the ePA backend can complete the handshake with attacker-controlled keys, derive the K2 session encryption keys, and read, modify, or inject all inner HTTP traffic including patient consent decisions, medication data, document operations, authorization tokens, and entitlement queries. Affected versions: - 1.0.0-SNAPSHOT We recommend updating to: 2026-05-20. CVSS 9.1 · our assessment: act_now Reference: https://github.com/med-united/epa4all/security/advisories/GHSA-vvh7-x6c7-46gh Details: https://vuln.today/cve/CVE-2026-48021