CVE-2026-29140: S/MIME Signature Additional Certificate
Published Apr 2, 2026
·Updated
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 Software
2 affected components
SEPPmail SEPPmail Secure Email Gateway<15.0.3
SEPPmail Secure Email Gateway<15.0.3
Event History
Apr 2, 2026
CVE Published
via MITRE·08:27 AM
Data Sourced
via MITRE·08:27 AM
DescriptionWeakness
Data Sourced
via NVD·09:16 AM
DescriptionSeverityWeaknessAffected Software
Frequently Asked Questions
1
What is the severity of CVE-2026-29140?
CVE-2026-29140 is considered a high severity vulnerability as it allows an attacker to manipulate S/MIME certificates.
2
How do I fix CVE-2026-29140?
To fix CVE-2026-29140, update your SEPPmail Secure Email Gateway to version 15.0.3 or later.
3
What type of attack is possible with CVE-2026-29140?
CVE-2026-29140 allows attackers to use their own certificates for encrypting emails sent to victims.
4
Who is affected by CVE-2026-29140?
All users of SEPPmail Secure Email Gateway versions prior to 15.0.3 are affected by CVE-2026-29140.
5
What software is vulnerable to CVE-2026-29140?
The vulnerability CVE-2026-29140 affects SEPPmail Secure Email Gateway versions before 15.0.3.