CVE-2026-20353: Cisco Secure Email

Critical severity, CVSS 9.8. EPSS: 0.4% chance of exploitation in the next 30 days.

As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco Secure Email Gateway and Cisco Secure Email and Web Manager engineering team has conducted a comprehensive internal security review. This review resulted in software hardening releases that address multiple internally discovered vulnerabilities. The vulnerabilities tracked by CVE-2026-20353 are related to issues with improper control of a resource through its lifetime that are grouped under the Common Weakness Enumeration (CWE) Pillar CWE-664.

Affected products

• Cisco Cisco Secure Email: version 14.0.0-698 only; version 13.5.1-277 only; version 13.0.0-392 only; version 14.2.0-620 only; version 13.0.5-007 only; version 13.5.4-038 only; …

Published 2026-09-14. Last modified 2026-09-15.