VAU traffic hijacking via discarded signature result
Published May 26, 2026 · Updated May 26, 2026
Improper certificate validation in Oviva AG epa4all-client before 1.2.1 allows man-in-the-middle attackers to hijack VAU traffic. SignedPublicKeysTrustValidatorImpl.isTrusted() discards Signature.verify()'s false result and accepts substituted public keys after unrelated chain and OCSP checks. An adjacent-network position is required; a successful relay can read and alter ePA documents and authorization flows without interrupting service.
Summary
What happened
Improper certificate validation in Oviva AG epa4all-client before 1.2.1 allows man-in-the-middle attackers to hijack VAU traffic. SignedPublicKeysTrustValidatorImpl.isTrusted() discards Signature.verify()'s false result and accepts substituted public keys after unrelated chain and OCSP checks. An adjacent-network position is required; a successful relay can read and alter ePA documents and authorization flows without interrupting service.
The record
- CVE
- CVE-2026-44900
- Published
- May 26, 2026
- Updated
- May 26, 2026
- Vendor
- Oviva AG
- Product
- epa4all-client
- Classifications
- CWE-295, T1557
- Attack vector
- adjacent
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 26, 2026CVE publishedPublication date reported by the CVE source.
- May 26, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=< 1.2.1
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Public exploit references
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Technologies
Your stack
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Your stack
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