PT-2026-29697 · Seppmail · Seppmail Secure Email Gateway

Andris Suter-Dörig + 2 · Published 2026-04-02 · Updated 2026-04-02 · CVE-2026-29140

Positive Technologies (AI Summary)

CVSS v4.0

7.7

High

Base vector

AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:H/SI:N/SA:N

Name of the Vulnerable Software and Affected Versions SEPPmail Secure Email Gateway versions prior to 15.0.3

Description SEPPmail Secure Email Gateway versions before 15.0.3 are susceptible to a flaw that allows an attacker to manipulate S/MIME signatures, leading to the use of attacker-controlled certificates for future encryption with a victim. This is achieved by adding these certificates to S/MIME signatures.

Recommendations Update SEPPmail Secure Email Gateway to version 15.0.3 or later.

Fix

Improper Certificate Validation

Weakness Enumeration

CWE-295

Related Identifiers

CVE-2026-29140

Affected Products

Seppmail Secure Email Gateway

References · 3

• https://nvd.nist.gov/vuln/detail/CVE-2026-29140 · Security Note
• https://twitter.com/CVEnew/status/2039647699268723093 · Twitter Post
• https://downloads.seppmail.com/extrelnotes/150/ERN15.0.html#seppmail-vulnerability-disclosure-1503 · Note