# CVE-2026-20353

## Summary

- **CVE ID:** CVE-2026-20353
- **Severity:** CRITICAL
- **CVSS Score:** 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
- **CWE:** CWE-664
- **Published:** Sep 14, 2026
- **Last Modified:** Sep 15, 2026

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

## References

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

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.40%
- **EPSS Percentile:** 33.4

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._