CVE-2026-20355 — Cisco Secure Email S/MIME Ciphertext Decryption Vulnerabilty
Multiple vulnerabilities in the Secure/Multipurpose Internet Mail Extensions (S/MIME) decryption functionality of Cisco Secure Email could allow an unauthenticated, remote attac…
Published: 2026-09-02 · CVSS: 5.9 · CVSS 3.1
Multiple vulnerabilities in the Secure/Multipurpose Internet Mail Extensions (S/MIME) decryption functionality of Cisco Secure Email could allow an unauthenticated, remote attacker to recover plain text from encrypted email messages. These vulnerabilities are due to insufficient validation of message integrity. An attacker could exploit these vulnerabilities by using a machine-in-the-middle technique to intercept and modify traffic between email gateways. A successful exploit could allow the attacker to obtain plaintext content from the encrypted communication.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7