ePA 3.x Integration: VAU Server Authentication Bypass via Circular Certificate Trust

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-52723
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-18 17:16:59 UTC
Updated2026-08-18 18:18:20 UTC
DescriptionePA 3.x Integration implements the authorization workflow and writes Medical Information Objects to Germany's electronic patient record. Prior to 1.3.0, ePA 3.x Integration performs VAU server certificate validation in app/vau/VAUProtokoll.py without anchoring the signed_vau_server_pub_keys and AUT_VAU_CertData certificate path to independent trusted material. A network-positioned attacker between the DiGA backend and the ePA system can intercept the VAU handshake, supply attacker-controlled certificate and key material, and satisfy the circular trust relationship. Because TLS certificate verification is also disabled in affected versions, no independent server-authentication layer prevents the attack. The attacker can impersonate the VAU server, control the negotiated session keys, and read or modify all encrypted VAU traffic. This issue is fixed in version 1.3.0.

Risk And Classification

Primary CVSS: v3.1 9.1 CRITICAL from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Problem Types: CWE-295 | CWE-295 CWE-295: Improper Certificate Validation

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary9.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
3.1CNADECLARED9.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Fbeta-GmbH EPA3-Service-OpenSource affected < 1.3.0 Not specified

References

ReferenceSourceLinkTags
www.machinespirits.de/advisory/a1da93 [email protected] www.machinespirits.de
github.com/fbeta-GmbH/ePA3-Service-OpenSource/security/advisories/GHSA-q... [email protected] github.com
github.com/fbeta-GmbH/ePA3-Service-OpenSource/releases/tag/1.3.0 [email protected] github.com
github.com/fbeta-GmbH/ePA3-Service-OpenSource/pull/12 [email protected] github.com
github.com/fbeta-GmbH/ePA3-Service-OpenSource/commit/197c8c7fc41675f19c7... [email protected] github.com
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