CVE-2026-29143

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.

CVSS 4.0

7.8CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:H/SA:N

CVSS 3.1

9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS

0.2% chance of exploitation in the next 30 days; higher than 16% of CVEs (scores of 2026-10-26)

CWE

CWE-20

Published

2026-04-02

Modified

2026-10-26

Record from

the NVD, synced 2026-10-26

Affected

• seppmail:secure_email_gateway

References

• https://downloads.seppmail.com/extrelnotes/150/ERN15.0.html#seppmail-vulnerability-disclosure-1503

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