All Advisories

gematik Authenticator

Authentication Flow Hijack

The gematik Authenticator is vulnerable to authentication flow hijacking, potentially allowing attackers to authenticate with the identities of victim users who click on a malicious deep link.

This advisory contains limited information during coordinated disclosure. Please check back later for full details.

Authored byVolker Schönefeld and Simon Weber2026-03-26
SeverityCriticalCVSS 9.3CVSS 3.1 VectorAV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:NCWECWE-940 (Improper Verification of Source of a Communication Channel)Productgematik AuthenticatorAffected VersionsAll versions prior to v4.16.0Fixed Inv4.16.0CVECVE-2026-33875GHSAGHSA-qg87-cf56-2rmr

Description

The gematik Authenticator is vulnerable to authentication flow hijacking. Attackers could potentially trick users into clicking a malicious link, which could allow the attacker to authenticate with the identity of the victim.

Impact

  • Unauthorized access to healthcare applications under the identity of the victim.

Mitigation

Update the gematik Authenticator to version 4.16.0 or greater.

References

How We Can Help

Who We Are

The security researchers behind this advisory.

Dr. Simon Weber Profile

Dr. rer. nat. Simon Weber

Senior Pentester & MedSec Researcher

I evaluate your SaMD with the same industry-defining security insight I contributed to the BAK MV for the revision of the B3S standard.

  • PhD on Hospital Cybersecurity
  • Critical vulnerabilities found in hospital systems
  • Alumni of THB MedSec Research Group
  • gematik Security Hero
Volker Schönefeld Profile

Dipl.-Inf. Volker Schönefeld

Senior Application Security Expert

As a former CTO and developer turned pentester, I work alongside your team to uncover vulnerabilities and find solutions that fit your architecture.

  • 20+ years as CTO, 50M+ app downloads
  • Architected and secured large-scale IoT fleets
  • Certified Web Exploitation Specialist
  • gematik Security Hero

Looking for a Penetration Test?

Machine Spirits specializes in security assessments for medical devices and healthcare IT. From MDR penetration testing to C5 cloud compliance, we help MedTech companies meet regulatory requirements.