CVE-2026-20354
MediumCVSS 5.9Exploitation Probability (EPSS)
Low risk4th percentile - higher than 4% of all known CVEs
Summary
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.
Risk Assessment
Organizations using Cisco Secure Email may experience disclosure of encrypted message content, potentially leading to data confidentiality breach.
Recommendation
Apply updates provided by Cisco for Cisco Secure Email to fix the vulnerabilities, and monitor email traffic for suspicious modifications.
Other vulnerabilities in Cisco Secure Email
Original NVD description (English source)
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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS