CVE-2026-2747 is a vulnerability identified in SEPPmail Secure Email Gateway versions before 15.0.1, categorized under CWE-200, which concerns the exposure of sensitive information to unauthorized actors. The root cause is the gateway's handling of inline PGP-encrypted messages: it decrypts these messages but fails to isolate the decrypted content from adjacent unencrypted data. This improper separation can cause sensitive decrypted information to be inadvertently exposed to unauthorized parties, potentially through logs, error messages, or other processing mechanisms within the gateway. The vulnerability is exploitable remotely without requiring authentication or user interaction, increasing the risk of exploitation. The CVSS 4.0 vector indicates a network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), and a low confidentiality impact (VC:L), with no impact on integrity or availability. The scope is high (SC:H), meaning the vulnerability affects components beyond the vulnerable component itself. No known exploits have been reported in the wild, but the vulnerability’s nature suggests it could be leveraged to leak sensitive email content if exploited. SEPPmail Secure Email Gateway is widely used in enterprise environments for secure email transmission, making this vulnerability relevant for organizations relying on PGP encryption for confidentiality.

The primary impact of CVE-2026-2747 is the potential unauthorized disclosure of sensitive information contained within decrypted PGP messages. This compromises the confidentiality of email communications, which can lead to data breaches involving personal, financial, or proprietary information. Organizations in regulated industries such as finance, healthcare, and government sectors are particularly at risk due to compliance requirements around data privacy. Although the vulnerability does not affect data integrity or availability, the exposure of sensitive content can damage organizational reputation, result in regulatory penalties, and facilitate further attacks such as phishing or social engineering. Since exploitation requires no authentication and can be performed remotely, attackers could target vulnerable SEPPmail gateways to intercept decrypted content. The absence of known exploits in the wild reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits once the vulnerability details become widely known.

To mitigate CVE-2026-2747, organizations should promptly upgrade SEPPmail Secure Email Gateway to version 15.0.1 or later, where the vulnerability has been addressed by properly isolating decrypted inline PGP content from unencrypted data. Until the upgrade is applied, administrators should consider implementing strict network segmentation and access controls to limit exposure of the gateway to untrusted networks. Monitoring and logging should be enhanced to detect unusual access patterns or data leakage attempts. Additionally, organizations should review email processing and logging configurations to ensure decrypted content is not inadvertently stored or exposed. Employing end-to-end encryption practices that minimize reliance on gateway decryption, or using alternative secure email solutions with robust handling of encrypted content, can also reduce risk. Regular vulnerability scanning and penetration testing focused on email gateway components will help identify residual risks. Finally, educating users and administrators about the risks associated with decrypted email content exposure is recommended.