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CVE-2026-29143

Seppmail Secure Email Gateway vulnerability

9.1 CRITICALEPSS 0.43%
  1. Published2 Apr 2026

Description

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 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected products

Seppmail Secure Email Gateway< 15.0.3

Remediation

Fixed in
Seppmail Secure Email Gateway≥ 15.0.3

References

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Frequently asked

Is CVE-2026-29143 being actively exploited?

CVE-2026-29143 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.43%.

How severe is CVE-2026-29143?

CVE-2026-29143 has a CVSS 3.1 base score of 9.1, rated critical. EPSS estimates a 0.43% probability of exploitation.

Which products are affected by CVE-2026-29143?

Affected products include Seppmail Secure Email Gateway.

How do I fix CVE-2026-29143?

Upgrade affected software to a fixed version, for example Seppmail Secure Email Gateway 15.0.3 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-29143 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.