Authorization Workflow Vulnerability in ePA 3.x Integration by fbeta GmbH

CVE-2026-50577

What is CVE-2026-50577?

The ePA 3.x Integration product contains a significant vulnerability in its authorization workflow, specifically in versions prior to 1.3.0. This flaw occurs due to the failure to update the request_counter while constructing VAU messages, leading to the reuse of AES-GCM nonce and key combinations. An attacker can exploit this weakness by analyzing repeated ciphertexts to recover sensitive plaintext data, such as medical records, leveraging predictable headers and fields. Additionally, the vulnerability allows for sophisticated attacks, including the recovery of the GHASH authentication key via the Joux forbidden attack, enabling the injection of forged messages. The product version 1.3.0 addresses this issue, enhancing security measures against replay and ordering attacks.

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