---
title: "CVE-2026-20353: CVE-2026-20353"
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."
url: https://panop.io/threat-heartbeat/CVE-2026-20353/
---

# CVE-2026-20353 CVE-2026-20353

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.

CVSS base score 9.8 /10

Critical

CISA KEV

Not listed

Public exploit

None known

EPSS

0.40% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-20353)

## Details

CVSS vector

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

Published

14 September 2026

Updated

15 October 2026

Weakness

[CWE-664](https://cwe.mitre.org/data/definitions/664.html)

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-20353](https://nvd.nist.gov/vuln/detail/CVE-2026-20353)
- [https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-hardening-esa-dfCrfXkm](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](https://www.cve.org/Media/News/item/blog/2026/06/16/Preserving-Vulnerability-Level-Identification)

[← All CVEs](https://panop.io/threat-heartbeat/)

## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

Panop answers these inside your environment, for this CVE and every other finding.

[Book a demo](https://panop.io/demo)