# CVE-2026-44900: Oviva epa4all-client signature bypass in SignedPublicKeysTrustValidator

Source: https://junglewise.ai/threats/cve-2026-44900-oviva-epa4all-client-signature-bypass-in  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-26. Updated: 2026-06-09  
License: CC BY 4.0 with a link back

CVE-2026-44900 · Severity: high · CVSS 8.1 · Published 2026-05-26

The epa4all-client library, used for interacting with electronic patient records, contains a flaw that fails to properly verify digital signatures. This allows an attacker on the same network to bypass security checks and potentially access or modify sensitive health data. The vulnerability effectively disables the trust mechanism intended to ensure that communications are authentic.

Technologies: [com.oviva.telematik:epa4all-client (Maven)](https://junglewise.ai/threats/technologies/com-oviva-telematik-epa4all-client), [Oviva AG Epa4all-Client](https://junglewise.ai/threats/technologies/epa4all-client). Vendors: [Maven](https://junglewise.ai/threats/vendors/maven), [Oviva AG](https://junglewise.ai/threats/vendors/oviva-ag).

## Quick answers

**Is CVE-2026-44900 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-44900 being exploited in the wild.

**How severe is CVE-2026-44900?** High severity, with a CVSS score of 8.1, published 26 May 2026.

**Which products and versions are affected?** com.oviva.telematik:epa4all-client (Maven) <= 1.2.0, ECOSYSTEM:introduced=0,fixed=1.2.1; Oviva AG Epa4all-Client < 1.2.1, <= 1.2.0.

**Is there a fix for CVE-2026-44900?** Yes. com.oviva.telematik:epa4all-client (Maven): upgrade to 1.2.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-44900 attacked?** It is attacked from the adjacent network, in a software library.

**Am I affected by CVE-2026-44900?** Check whether you run com.oviva.telematik:epa4all-client (Maven) or Oviva AG Epa4all-Client at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- com.oviva.telematik:epa4all-client (Maven): upgrade to 1.2.1 or later

  ```sh
  # set com.oviva.telematik:epa4all-client to 1.2.1 in your pom.xml or build.gradle
  ```


## Technical details

A signature bypass vulnerability exists in the SignedPublicKeysTrustValidatorImpl.isTrusted() method of the epa4all-client library. The implementation performs certificate chain validation and OCSP checks but discards the boolean return value of the Signature.verify() call. Consequently, the method returns true for any signature that is structurally valid, regardless of whether the cryptographic signature actually matches the data. An attacker on an adjacent network can exploit this to bypass VAU (Vertrauenswürdige Ausführungsumgebung) signature requirements. The issue is addressed in version 1.2.1.

## Affected products

- oviva-ag epa4all-client <= 1.2.0

## Identifiers

- CVE-2026-44900
- GHSA-g8r3-5hwf-qp96

## Timeline

- 2026-05-06: disclosed: Initial disclosure by researchers
- 2026-05-08: advisory: GitHub Advisory published
- 2026-05-26: patched: NVD publication date

## References

- [https://api.github.com/users/snomi](https://api.github.com/users/snomi)
- [https://github.com/snomi](https://github.com/snomi)
- [https://api.github.com/users/snomi/gists%7B/gist_id%7D](https://api.github.com/users/snomi/gists%7B/gist_id%7D)
- [https://api.github.com/users/snomi/repos](https://api.github.com/users/snomi/repos)
- [https://avatars.githubusercontent.com/u/19928196?v=4](https://avatars.githubusercontent.com/u/19928196?v=4)
- [https://api.github.com/users/snomi/events%7B/privacy%7D](https://api.github.com/users/snomi/events%7B/privacy%7D)

## Related threats

- [Oviva epa4all-client improper TLS certificate validation](https://junglewise.ai/threats/cve-2026-45574-oviva-epa4all-client-improper-tls-certificate-validation)
- [oviva-ag epa4all-client signature verification bypass in IDP discovery](https://junglewise.ai/threats/cve-2026-45575-oviva-ag-epa4all-client-signature-verification-bypass-in-idp)