Cyber Resilience

CVE-2026-33875

Gematik Authenticator ≤ 4.16.0

Published
27 March 2026
Modified
03 April 2026
Patch / advisory
View advisory
CVSS Score v3.1 9.3
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
EPSS Score 0.0027 18th percentile
Risk Priority 64 floored blend · peak EPSS

Summary

CVE-2026-33875 is a critical-severity Improper Verification of Source of a Communication Channel (CWE-940) vulnerability in Gematik Authenticator. Its CVSS base score is 9.3 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique ARP Cache Poisoning (T1557.002); ranked at the 18th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to AC-17 (Remote Access) and IA-3 (Device Identification and Authentication) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2026-33875 affects the Gematik Authenticator, a component used to securely authenticate users for login to digital health applications. Versions prior to 4.16.0 are vulnerable to authentication flow hijacking, classified under CWE-940. The issue has a CVSS v3.1 base score of 9.3 (AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N), indicating high severity due to its network accessibility, low attack complexity, lack of required privileges, reliance on user interaction, expanded scope, and significant impacts on confidentiality and integrity.

Remote attackers with no privileges can exploit this vulnerability by crafting malicious deep links that, when clicked by victims, hijack the authentication flow. This allows attackers to authenticate using the identities of victim users, potentially granting unauthorized access to digital health services tied to the victim's account.

Advisories, including the Gematik GitHub Security Advisory (GHSA-qg87-cf56-2rmr) and the Machine Spirits advisory (https://www.machinespirits.com/advisory/f41e56/), recommend updating the Gematik Authenticator to version 4.16.0 or greater to apply the patch. No workarounds are known.

OWASP Top 10 for Web (2025)

A07:2025 Authentication Failures

EU & UK References

Vulnerability Data

Gematik Authenticator securely authenticates users for login to digital health applications. Versions prior to 4.16.0 are vulnerable to authentication flow hijacking, potentially allowing attackers to authenticate with the identities of victim users who click on a malicious deep link. Update…

more

Gematik Authenticator to version 4.16.0 or greater to receive a patch. There are no known workarounds.

CWE(s)
CWE-940

Related Threats

MITRE ATT&CK Enterprise Techniques

T1557.002 ARP Cache Poisoning Credential Access
Adversaries may poison Address Resolution Protocol (ARP) caches to position themselves between the communication of two or more networked devices.
attack.mitre.org →
T1557 Adversary-in-the-Middle Credential Access
Adversaries may attempt to position themselves between two or more networked devices using an adversary-in-the-middle (AiTM) technique to support follow-on behaviors such as [Network Sniffing](https://attack.
attack.mitre.org →
T1557.001 Name Resolution Poisoning and SMB Relay Credential Access
By responding to LLMNR/NBT-NS/mDNS network traffic, adversaries may spoof an authoritative source for name resolution to force communication with an adversary controlled system.
attack.mitre.org →
T1557.003 DHCP Spoofing Credential Access
Adversaries may redirect network traffic to adversary-owned systems by spoofing Dynamic Host Configuration Protocol (DHCP) traffic and acting as a malicious DHCP server on the victim network.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2025-40820Shared CWE-940
CVE-2025-23019Shared CWE-940
CVE-2023-3663Shared CWE-940
CVE-2025-13086Shared CWE-940
CVE-2025-42978Shared CWE-940
CVE-2024-40503Shared CWE-940
CVE-2026-48745Shared CWE-940
CVE-2019-25613Shared CWE-940
CVE-2025-62439Shared CWE-940
CVE-2025-61932Shared CWE-940

Affected Assets

gematik
authenticator
≤ 4.16.0

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V3.5.3
  • V10.6.2
  • V15.2.4

Mitigating Controls (NIST 800-53 r5) AI

IA-3 Device Identification and Authentication good match

IA-3 requires unique identification and authentication of devices before any communication channel is established, directly stopping acceptance of unverified origins.

AC-17 Remote Access good match

AC-17 mandates documented restrictions and authentication requirements for remote access, blocking channels whose origins are not properly verified.

SC-23 Session Authenticity partial match

SC-23 protects session authenticity, ensuring the source of an established communication channel is verified and cannot be spoofed.

SC-7 Boundary Protection partial match

SC-7 enforces monitoring and control at external and key internal interfaces, preventing channels from unverified sources via boundary rules.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.AA-03 full match
prevents

Authentication of users/services/hardware directly enforces source verification for communication channels.

PR.AA-04 mostly match
prevents

Verifying identity assertions prevents spoofed channel origins but does not cover all channel-establishment scenarios.

PR.IR-01 partial match
prevents

Network protections reduce unauthorized channel usage but do not specifically require origin verification at channel setup.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.5 Secure authentication mostly match
prevents

Secure authentication mechanisms verify the identity and origin of communication channel initiators.

A.8.20 Networks security partial match
degrades

Network security controls enforce source verification and channel authentication for incoming communications.

A.8.21 Security of network services partial match
degrades

Security of network services includes validating the origin of service requests and connections.

A.8.22 Segregation of networks partial match
mitigates

Network segregation limits exposure but does not directly verify source of individual channels.

A.8.24 Use of cryptography partial match
prevents

Cryptography can support channel authentication but does not inherently verify source without proper implementation.

A.8.26 Application security requirements partial match
prevents

Application security requirements may specify origin checks but do not mandate them.

References