CVE-2026-29140: Seppmail Secure Email Gateway

Medium severity, CVSS 5.3. EPSS: 0.2% chance of exploitation in the next 30 days.

SEPPmail Secure Email Gateway before version 15.0.3 allows an attacker to cause attacker-controlled certificates to be used for future encryption to a victim by adding the certificates to S/MIME signatures.

Affected products

• Seppmail Secure Email Gateway: before 15.0.3 (fixed in 15.0.3)

Published 2026-04-02. Last modified 2026-06-17.