CVE-2026-20354 — Cisco Secure Email S/MIME Ciphertext Decryption Vulnerabilty

Description (CNA)

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.

Affected (CNA)

Vendor / product	Versions
Cisco / Cisco Secure Email	affected 14.0.0-698; affected 13.5.1-277; affected 13.0.0-392; affected 14.2.0-620; affected 13.0.5-007; affected 13.5.4-038; affected 14.2.1-020; affected 14.3.0-032; affected 15.0.0-104; affected 15.0.1-030; affected 15.5.0-048; affected 15.5.1-055; affected 15.5.2-018; affected 16.0.0-050; affected 15.0.3-002; affected 16.0.0-054; affected 15.5.3-022; affected 16.0.1-017; affected 15.5.4-012; affected 16.0.4-016; affected 15.0.5-016; affected 16.0.2-112; affected 16.0.3-044; affected 16.5.0-780

Vendor / product

Versions

Cisco / Cisco Secure Email

affected 14.0.0-698; affected 13.5.1-277; affected 13.0.0-392; affected 14.2.0-620; affected 13.0.5-007; affected 13.5.4-038; affected 14.2.1-020; affected 14.3.0-032; affected 15.0.0-104; affected 15.0.1-030; affected 15.5.0-048; affected 15.5.1-055; affected 15.5.2-018; affected 16.0.0-050; affected 15.0.3-002; affected 16.0.0-054; affected 15.5.3-022; affected 16.0.1-017; affected 15.5.4-012; affected 16.0.4-016; affected 15.0.5-016; affected 16.0.2-112; affected 16.0.3-044; affected 16.5.0-780

CWE

CWE-354

References

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-esa-smime-disc-dzw4rEdY

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.