CVE-2026-44900
epa4all-client: VAU Signature bypass
epa4all-client is the Java Client for epa4all / ePA 3.0 in the Telematik Infrastruktur. Prior to 1.2.1, in SignedPublicKeysTrustValidatorImpl.isTrusted(), the ECDSA signature verification at line 45 discards the boolean return value of Signature.verify(). The method performs certificate chain validation, OCSP check, and signature algorithm setup, but never checks whether the signature actually matches. For any structurally valid signature, it returns true. This vulnerability is fixed in 1.2.1.
Attack profile
How easy it is to exploit
- Attack vector
- Adjacent network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
epa4all-client: VAU Signature bypass
epa4all-client is the Java Client for epa4all / ePA 3.0 in the Telematik Infrastruktur. Prior to 1.2.1, in SignedPublicKeysTrustValidatorImpl.isTrusted(), the ECDSA signature verification at line 45 discards the boolean return value of Signature.verify(). The method performs certificate chain validation, OCSP check, and signature algorithm setup, but never checks whether the signature actually matches. For any structurally valid signature, it returns true. This vulnerability is fixed in 1.2.1.
- Record
CVE-2026-44900- CVSS 3.1
- 8.1 High
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N - Weakness
- CWE-295
- Updated
- 2026-11-02
EUVDEUVD-2026-32002
epa4all-client is the Java Client for epa4all / ePA 3.0 in the Telematik Infrastruktur. Prior to 1.2.1, in SignedPublicKeysTrustValidatorImpl.isTrusted(), the ECDSA signature verification at line 45 discards the boolean return value of Signature.verify(). The method performs certificate chain validation, OCSP check, and signature algorithm setup, but never checks whether the signature actually matches. For any structurally valid signature, it returns true. This vulnerability is fixed in 1.2.1.
- Record
EUVD-2026-32002- CVSS 3.1
- 8.1 High
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-g8r3-5hwf-qp96
epa4all-client has a VAU Signature bypass
Impact
In SignedPublicKeysTrustValidatorImpl.isTrusted(), the ECDSA signature verification at line 45 discards the boolean return value of Signature.verify(). The method performs certificate chain validation, OCSP check, and signature algorithm setup, but never checks whether the signature actually matches. For any structurally valid signature, it returns true.
Patches
Patched in #34.
Workarounds
None.
Resources
Credits
Machine Spirits ([email protected])
- Dr. rer. nat. Simon Weber
- Dipl.-Inf. Volker Schönefeld
- Chiara Fliegner
- Record
GHSA-g8r3-5hwf-qp96- CVSS 3.1
- 8.1 High
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N - Weakness
- CWE-295
- Updated
- 2026-11-02
NVD
epa4all-client is the Java Client for epa4all / ePA 3.0 in the Telematik Infrastruktur. Prior to 1.2.1, in SignedPublicKeysTrustValidatorImpl.isTrusted(), the ECDSA signature verification at line 45 discards the boolean return value of Signature.verify(). The method performs certificate chain validation, OCSP check, and signature algorithm setup, but never checks whether the signature actually matches. For any structurally valid signature, it returns true. This vulnerability is fixed in 1.2.1.
- Record
CVE-2026-44900- CVSS 3.1
- 8.1 High
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N - Weakness
- CWE-295
- Updated
- 2026-11-02
OSV
epa4all-client: VAU Signature bypass
epa4all-client is the Java Client for epa4all / ePA 3.0 in the Telematik Infrastruktur. Prior to 1.2.1, in SignedPublicKeysTrustValidatorImpl.isTrusted(), the ECDSA signature verification at line 45 discards the boolean return value of Signature.verify(). The method performs certificate chain validation, OCSP check, and signature algorithm setup, but never checks whether the signature actually matches. For any structurally valid signature, it returns true. This vulnerability is fixed in 1.2.1.
- Record
CVE-2026-44900- CVSS 3.1
- 8.1 High
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N - Weakness
- CWE-295
- Updated
- 2026-11-02
OSVGHSA-g8r3-5hwf-qp96
epa4all-client has a VAU Signature bypass
Impact
In SignedPublicKeysTrustValidatorImpl.isTrusted(), the ECDSA signature verification at line 45 discards the boolean return value of Signature.verify(). The method performs certificate chain validation, OCSP check, and signature algorithm setup, but never checks whether the signature actually matches. For any structurally valid signature, it returns true.
Patches
Patched in #34.
Workarounds
None.
Resources
Credits
Machine Spirits ([email protected])
- Dr. rer. nat. Simon Weber
- Dipl.-Inf. Volker Schönefeld
- Chiara Fliegner
- Record
GHSA-g8r3-5hwf-qp96- CVSS 3.1
- 8.1 High
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N - Weakness
- CWE-295
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
com.oviva.telematik:epa4all-clientMaven |
through 1.2.0 | 1.2.1 |
com.oviva.telematik:epa4all-clientMaven |
before 1.2.1, plus listed versions 0.0.2-rc.00.0.40.0.50.0.70.0.8 Show 6 moreShow less1.0.01.0.21.0.31.1.01.1.11.2.0 |
1.2.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-44900 is a high vulnerability (CVSS 8.1) in Com.oviva.telematik Epa4all-client, published May 8, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.12%, the 1st percentile. Fixed in com.oviva.telematik:epa4all-client 1.2.1.
References
github.com/oviva-ag/epa4all-client/security/advisories/GHSA-g8r3-5hwf-qp96
machinespirits.com/advisory/d76aec
nvd.nist.gov/vuln/detail/CVE-2026-44900