What’s Vulnerable › Vulnerabilities

CVE-2026-20353: Cisco Secure Email Gateway Security Hardening Release

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-14 · updated 2026-09-15
• Weakness: CWE-664

Description

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 Email Security Appliance (ESA): 14.0.0-698, 13.5.1-277, 13.0.0-392, 14.2.0-620, 13.0.5-007, 13.5.4-038 (+17)

In the news

• Cisco Secure Email Gateway and Secure Email and Web Manager Security Hardening Release: September 2026

References

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-hardening-esa-dfCrfXkm
• https://www.cve.org/Media/News/item/blog/2026/06/16/Preserving-Vulnerability-Level-Identification

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