Certificate Injection Vulnerability in SEPPmail Secure Email Gateway

Publication date: 2026-04-02

Last updated on: 2026-04-16

Assigner: Switzerland Government Common Vulnerability Program

Description

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.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-04-02

Last Modified

2026-04-16

Generated

2026-07-06

AI Q&A

2026-04-02

EPSS Evaluated

2026-07-05

NVD

CVE-2026-29140

EUVD

EUVD-2026-18160

Affected Vendors & Products

Vendor	Product	Version / Range
seppmail	secure_email_gateway	to 15.0.3 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-295	The product does not validate, or incorrectly validates, a certificate.

Attack-Flow Graph

Impact Analysis

The vulnerability can lead to an attacker controlling the certificates used for encrypting emails to the victim. This could compromise the confidentiality of future encrypted communications, potentially allowing unauthorized access to sensitive information.

Executive Summary

This vulnerability affects SEPPmail Secure Email Gateway versions before 15.0.3. It allows an attacker to insert attacker-controlled certificates into S/MIME signatures. As a result, these malicious certificates can be used for future encryption directed at the victim.

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