Email Security Flaw in Cisco Secure Email Allows Remote Exploitation

CVE-2026-20354

What is CVE-2026-20354?

Multiple vulnerabilities in the S/MIME decryption functionality of Cisco Secure Email could allow unauthenticated remote attackers to decrypt intercepted encrypted email messages. These vulnerabilities arise from insufficient validation of message integrity, enabling attackers to leverage a machine-in-the-middle technique to intercept and manipulate communications between email gateways. By exploiting this flaw, attackers may gain access to plaintext content of sensitive email communications, posing significant risks to data integrity and confidentiality.

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