Vulnerability · Published Mar 4, 2026 · Assigned by NCSC.ch
CVE-2026-27443S/MIME Decryption Tag Sanitization Bypass
High 8.2
In plain English
A high-severity improper input 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 0.2% (higher than 16% of all known vulnerabilities).
Severity (CVSS 4.0)8.2High
Exploit odds (30 days)0.2%top 83.9% 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 does not properly sanitize the headers from S/MIME protected MIME entities, allowing an attacker to control trusted headers.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| SEPPmail | Secure Email Gateway | 0 – before 15.0.1 |
Weakness: CWE-20 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:L/SA:N