What is CVE-2026-2748?

CVE-2026-2748 is a medium-severity vulnerability in Seppmail Secure Email Gateway, classified under Improper Certificate Validation. CVSS score: 5.3/10. Published 2026-03-04.

How severe is CVE-2026-2748?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Vulnerability in Seppmail Secure Email Gateway

CVE-2026-2748

SEPPmail Secure Email Gateway before version 15.0.1 improperly validates S/MIME certificates issued for email addresses containing whitespaces, allowing signature spoofing.

Vulnerability class: Improper Certificate Validation

Published 2026-03-04 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.

EPSS exploit prediction

EPSS: 0.002 (7.7th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 8th percentile — 7.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.001 · newest: 0.002 · change: +0.001

Affected products

Seppmail Secure Email Gateway — versions 0
Seppmail

Weakness classification (CWE)

CWE-295 — Improper Certificate Validation

References

downloads.seppmail.com/extrelnotes/150/ERN15.0.html (release-notes, Vendor Advisory)

Frequently asked questions

What is CVE-2026-2748?: CVE-2026-2748 is a medium-severity vulnerability in Seppmail Secure Email Gateway, classified under Improper Certificate Validation. CVSS score: 5.3/10. Published 2026-03-04.
How severe is CVE-2026-2748?: Medium severity. CVSS v3 base score is 5.3 out of 10.