CVE-2026-50577
ePA 3.x Integration: AES-GCM Nonce Reuse via Frozen VAU Request Counter
Description
ePA 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 leaves request_counter unchanged in app/vau/VAUProtokoll.py while constructing VAU messages. The frozen client request counter causes the server side to reuse AES-GCM nonce and key combinations across responses. A network attacker who collects repeated ciphertexts can recover the XOR of plaintexts and use predictable inner HTTP headers and JSON fields to recover sensitive data, including patient health records. Repeated nonces can also enable recovery of the GHASH authentication key through the Joux forbidden attack, allowing forged AES-GCM messages and injection of malicious responses. The response-counter check also fails to maintain last_response_counter, weakening replay and ordering validation. This issue is fixed in version 1.3.0.
INFO
Published Date :
Aug. 18, 2026, 5:16 p.m.
Last Modified :
Oct. 22, 2026, 10:10 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 3.1 | HIGH | MITRE-CVE |
Solution
- Update ePA 3.x Integration to version 1.3.0.
- Ensure request_counter is properly managed.
- Implement robust nonce and key management.
- Strengthen replay and ordering validation.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-50577.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-50577 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-50577
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-50577 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-50577 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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CVE Translated by [email protected]
Oct. 22, 2026
Action Type Old Value New Value Added Translation Title: ePA3-Service-OpenSource de fbeta-GmbH, Description: La Integración ePA 3.x implementa el flujo de trabajo de autorización y escribe Objetos de Información Médica en el registro electrónico de pacientes de Alemania. Antes de la versión 1.3.0, la Integración ePA 3.x deja request_counter sin cambios en app/vau/VAUProtokoll.py al construir mensajes VAU. El contador de solicitudes del cliente congelado hace que el lado del servidor reutilice combinaciones de nonce y clave AES-GCM en las respuestas. Un atacante de red que recopila textos cifrados repetidos puede recuperar el XOR de los textos planos y usar encabezados HTTP internos y campos JSON predecibles para recuperar datos sensibles, incluyendo registros de salud de pacientes. Los nonces repetidos también pueden permitir la recuperación de la clave de autenticación GHASH a través del ataque prohibido de Joux, permitiendo mensajes AES-GCM falsificados e inyección de respuestas maliciosas. La verificación del contador de respuestas también falla en mantener last_response_counter, debilitando la validación de repetición y orden. Este problema está solucionado en la versión 1.3.0. -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Aug. 19, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-50577', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-08-19T14:52:41.729661Z'} -
New CVE Received by [email protected]
Aug. 18, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'fbeta-GmbH', 'product': 'ePA3-Service-OpenSource', 'versions': [{'status': 'affected', 'version': '< 1.3.0'}]}] Added Description ePA 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 leaves request_counter unchanged in app/vau/VAUProtokoll.py while constructing VAU messages. The frozen client request counter causes the server side to reuse AES-GCM nonce and key combinations across responses. A network attacker who collects repeated ciphertexts can recover the XOR of plaintexts and use predictable inner HTTP headers and JSON fields to recover sensitive data, including patient health records. Repeated nonces can also enable recovery of the GHASH authentication key through the Joux forbidden attack, allowing forged AES-GCM messages and injection of malicious responses. The response-counter check also fails to maintain last_response_counter, weakening replay and ordering validation. This issue is fixed in version 1.3.0. Added CVSS V3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N Added CWE CWE-323 Added Reference https://github.com/fbeta-GmbH/ePA3-Service-OpenSource/commit/85c4c516088c38b9cf2343f388ad67a6744e9814 Added Reference https://github.com/fbeta-GmbH/ePA3-Service-OpenSource/pull/10 Added Reference https://github.com/fbeta-GmbH/ePA3-Service-OpenSource/releases/tag/1.3.0 Added Reference https://github.com/fbeta-GmbH/ePA3-Service-OpenSource/security/advisories/GHSA-vmfm-3f7g-r9qg Added Reference https://www.machinespirits.de/advisory/df27cd