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7.8
SEPPmail Secure Email Gateway: Email Signature Spoofing
CVE-2026-2748
Summary
Certain email certificates are not properly validated, allowing attackers to fake email sender identities. This can lead to unauthorized emails appearing to come from trusted senders. Upgrading to version 15.0.1 or later is recommended to mitigate this risk.
What to do
No fix is available yet. Check with your software vendor for updates.
Affected software
| Vendor | Product | Affected versions | Fix available |
|---|---|---|---|
| seppmail | seppmail | <= 15.0.1 | – |
Original title
SEPPmail Secure Email Gateway before version 15.0.1 improperly validates S/MIME certificates issued for email addresses containing whitespaces, allowing signature spoofing.
Original description
SEPPmail Secure Email Gateway before version 15.0.1 improperly validates S/MIME certificates issued for email addresses containing whitespaces, allowing signature spoofing.
nvd CVSS3.1
5.3
nvd CVSS4.0
7.8
Vulnerability type
CWE-295
Improper Certificate Validation
Published: 4 Mar 2026 · Updated: 13 Mar 2026 · First seen: 6 Mar 2026