S/MIME Signature Vulnerability in SEPPmail Secure Email Gateway
CVE-2026-29140

7.7HIGH

Key Information:

Vendor

Seppmail

Status
Secure Email Gateway
Vendor
CVE Published:
2 April 2026

What is CVE-2026-29140?

The SEPPmail Secure Email Gateway prior to version 15.0.3 is susceptible to an S/MIME signature vulnerability that can allow an attacker to manipulate email communications by injecting attacker-controlled certificates. This issue permits unauthorized encryption of messages, potentially compromising sensitive information exchanged between victims.

Affected Version(s)

Secure Email Gateway 0 < 15.0.3

References

https://downloads.seppmail.com/extrelnotes/150/ERN15.0.ht...
release-notes

CVSS V4

Score:
7.7
Severity:
HIGH
Confidentiality:
None
Integrity:
Low
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Andris Suter-Dörig
Matteo Scarlata
Kenny Paterson
.