CVE-2026-44900
epa4all-client has a VAU Signature bypass
Description
### 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](https://github.com/oviva-ag/epa4all-client/pull/34). ### Workarounds None. ### Resources - [MS-OVIVA-EPA4ALL-d76aec](https://www.machinespirits.com/advisory/d76aec/) ### Credits [Machine Spirits](https://machinespirits.com) (contact@machinespirits.de) - Dr. rer. nat. Simon Weber - Dipl.-Inf. Volker Schönefeld - Chiara Fliegner
How to fix CVE-2026-44900
To remediate CVE-2026-44900, upgrade the affected package to a fixed version below.
- —upgrade to 1.2.1 or later
Is CVE-2026-44900 being exploited?
Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- from 0, < 1.2.1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | HIGH8.1 | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N |