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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.

PUBLISHED Reserved 2026-03-04 | Published 2026-04-02 | Updated 2026-04-02 | Assigner NCSC.ch




HIGH: 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

Problem types

CWE-20 Improper Input Validation

Product status

Default status
unaffected

Any version before 15.0.3
affected

Timeline

2025-10-31:Vulnerability disclosed to SEPPmail
2026-03-03:Version 15.0.3 released

Credits

Andris Suter-Dörig finder

Matteo Scarlata coordinator

Kenny Paterson coordinator

References

downloads.seppmail.com/extrelnotes/150/ERN15.0.html release-notes

cve.org (CVE-2026-29143)

nvd.nist.gov (CVE-2026-29143)

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