CVE-2026-20355

CVE Enrichment

CVSS: 5.9 MEDIUM
EPSS: 0.16%
EPSS Percentile: 4.87%
CISA KEV: Not listed

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.

Technical Details

CVSS Version: 3.1
CNA / NVD Source: [email protected]
Published: 03-Sep-2026 00:17
Last Modified: 03-Sep-2026 02:23
EPSS Date: 2026-10-22
CWE: CWE-345

CVSS Vector


            CVSS:3.1                            AV:N /
                            AC:H /
                            PR:N /
                            UI:N /
                            S:U /
                            C:H /
                            I:N /
                            A:N

References

[email protected]

Last enrichment sync: 22-Oct-2026 23:04
Sources: NVD · FIRST EPSS · CISA KEV
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Reported Context (1)

Internet Mail Extensions (S/MIME) decryption flaws in Secure Email, CVE-2026-20354 and CVE-2026-20355 (CVSS scores: 5.9), allow a machine-in-the-middle attacker to recover plaintext from mail passing Cisco Patches Critical Nexus 9000 Flaw Enabling Unauthenticated Remote Code Execution

CVE (7)

People (1)

Threat Actors (1)

MITRE ATT&CK (5)

Vendors (1)

Products (8)

Industries (1)

Countries (1)

Note: Related entities, including threat actors, malware, CVEs, MITRE ATT&CK techniques, vendors, products, tools, countries, and industries, are shown when they appear in the same reporting. Their presence does not necessarily mean they were targeted, compromised, vulnerable, responsible for the activity, or directly involved in the incident.