CVE-2026-29143

S/MIME Decryption Impersonation

Published Apr 2, 2026 CVSS 4.0 · 7.8 High EPSS < 1% KEV · Not listed
Description
SEPPmail Secure Email Gateway before version 15.0.3 does not properly authenticate the inner message of S/MIME-encrypted MIME entities, allowing an attacker to control trusted headers.

Remediation

No solution or workaround provided in the CVE record

Tracking

Sign in to view the affected projects.

Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Seppmail secure Email Gateway
CPEs cpe:2.3:a:seppmail:secure_email_gateway:*:*:*:*:*:*:*:*
Vendors & Products Seppmail secure Email Gateway
Metrics cvssV3_1

{'score': 9.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N'}

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description SEPPmail Secure Email Gateway before version 15.0.3 does not properly authenticate the inner message of S/MIME-encrypted MIME entities, allowing an attacker to control trusted headers.
Title S/MIME Decryption Impersonation
First Time appeared Seppmail
Seppmail seppmail Secure Email Gateway
Weaknesses CWE-20
CPEs cpe:2.3:a:seppmail:seppmail_secure_email_gateway:*:*:*:*:*:*:*:*
Vendors & Products Seppmail
Seppmail seppmail Secure Email Gateway
References
Metrics cvssV4_0

{'score': 7.8, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:H/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
NCSC.ch
Published
Updated
Apr 2, 2026, 1:34 PM
Reserved
Mar 4, 2026, 9:08 AM
Status
Analyzed
Published
Apr 2, 2026, 9:16 AM
Modified
Oct 26, 2026, 9:10 PM