CVE-2026-44900 epa4all-client: VAU Signature bypass
Attackers can bypass ECDSA signature verification in the epa4all-client library by exploiting a discarded boolean return value, allowing untrusted data to be accepted as valid.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-44900?
CVE-2026-44900 is a high-severity vulnerability in com.oviva.telematik epa4all-client, published on 26 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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.
Weakness: CWE-295
Which versions are affected by CVE-2026-44900?
2 open source packages ship an affected version, including com.oviva.telematik:epa4all-client.
| Package | Affected | Fixed in |
|---|---|---|
com.oviva.telematik:epa4all-client Maven | All versions | 1.2.1 |
com.oviva.telematik:epa4all-client Maven | All versions | 1.2.1 |
How do I fix CVE-2026-44900?
Upgrade com.oviva.telematik:epa4all-client to 1.2.1 or later.
Is CVE-2026-44900 being exploited?
There is no known exploitation of CVE-2026-44900 in the wild and no public exploit code.
Sources
Also known as GHSA-g8r3-5hwf-qp96.