CVE-2026-27443 S/MIME Decryption Tag Sanitization Bypass
Attackers can bypass S/MIME decryption tag sanitization to control trusted headers in SEPPmail Secure Email Gateway.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-27443?
CVE-2026-27443 is a high-severity vulnerability in SEPPmail Secure Email Gateway, published on 4 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
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.
Weakness: CWE-20
Which versions are affected by CVE-2026-27443?
It affects 1 product.
Products include Seppmail Seppmail.
How do I fix CVE-2026-27443?
No fix has been published for CVE-2026-27443 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-27443 being exploited?
There is no known exploitation of CVE-2026-27443 in the wild and no public exploit code.
Other vulnerabilities in SEPPmail Secure Email Gateway
Sources
Also known as GHSA-5v5x-g684-qwfj.