CVE-2026-29143: high-severity vulnerability in SEPPmail Secure Email Gateway
S/MIME Decryption Impersonation
Published
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.8epss 0.3%
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.
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
Affected products
SEPPmail · Secure Email GatewayRelated CVEs — SEPPmail Secure Email Gateway
In the same product, most dangerous first.
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