SEPTEMBER 17, 2026
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Case File

CVE-2026-20355

MEDIUM · CVSS 5.9 EPSS 0.15% Public Exploit

Source: NVD + CISA KEV + EPSS · Published 2026-09-02 · Last synced 2026-09-17

CyberRota Analysis

AI-Generated

Cisco Secure Email is vulnerable due to insufficient validation of message integrity in its S/MIME decryption functionality, allowing unauthenticated remote attackers to intercept and modify traffic between email gateways. This could enable attackers to recover plaintext from encrypted email messages, posing a risk to the confidentiality of sensitive communications. Organizations using Cisco Secure Email should prioritize addressing this vulnerability to safeguard their email security.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

Detected Signals
exploit

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2026-20355
Severity
MEDIUM
CVSS
5.9
EPSS
0.15%
Cisco

Original NVD Description

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.