CVE-2026-2747
Published: 04 March 2026
Summary
CVE-2026-2747 is a medium-severity Exposure of Sensitive Information to an Unauthorized Actor (CWE-200) vulnerability in Seppmail Seppmail. Its CVSS base score is 6.9 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 15.5th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 AC-4 (Information Flow Enforcement) and SC-4 (Information in Shared System Resources).
Deeper analysis
CVE-2026-2747 affects SEPPmail Secure Email Gateway versions prior to 15.0.1. The vulnerability arises because the software decrypts inline PGP messages without isolating the decrypted content from surrounding unencrypted email content. This flaw, classified under CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor), carries a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N), indicating high confidentiality impact with network accessibility, low attack complexity, and no requirements for privileges or user interaction.
An unauthorized remote attacker can exploit this vulnerability by sending a specially crafted email containing an inline PGP message to a targeted SEPPmail Secure Email Gateway. Upon processing, the gateway decrypts the PGP-encrypted content without proper isolation, potentially exposing sensitive information within the decrypted payload to the attacker through logs, processing artifacts, or other unencrypted contexts.
The vendor's extended release notes for SEPPmail version 15.0, available at https://downloads.seppmail.com/extrelnotes/150/ERN15.0.html#seppmail-vulnerability-disclosure, disclose the vulnerability and detail mitigation measures, recommending an upgrade to version 15.0.1 or later to address the issue.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-9384
Vulnerability details
SEPPmail Secure Email Gateway before version 15.0.1 decrypts inline PGP messages without isolating them from surrounding unencrypted content, allowing exposure of sensitive information to an unauthorized actor.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
The CVE describes remote exploitation of a public-facing email gateway via crafted emails that trigger improper PGP decryption and sensitive data exposure (CWE-200), directly enabling T1190.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly mitigates the CVE by remediating the specific flaw in PGP decryption isolation through timely application of vendor patches to version 15.0.1 or later.
Prevents unauthorized information transfer of decrypted PGP content via shared system resources like logs or processing artifacts during email gateway operations.
Enforces approved information flows to isolate decrypted sensitive PGP content from surrounding unencrypted email content, blocking exposure to unauthorized actors.