Vulnerability · Published Mar 4, 2026 · Assigned by NCSC.ch
CVE-2026-2748S/MIME Certificate Subject Whitespace
High 7.8
In plain English
A high-severity improper certificate validation in Secure Email Gateway from SEPPmail. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 3% of all known vulnerabilities).
Severity (CVSS 4.0)7.8High
Exploit odds (30 days)0.1%top 97.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
SEPPmail Secure Email Gateway before version 15.0.1 improperly validates S/MIME certificates issued for email addresses containing whitespaces, allowing signature spoofing.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| SEPPmail | Secure Email Gateway | 0 – before 15.0.1 |
Weakness: CWE-295 · 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