CriticalCisco Exploited

Critical [CVE-2026-20353 +4] Cisco Secure Email Gateway and Secure Email and Web Manager Security Hardening Release: September 2026

This critical-severity Cisco advisory covers CVE-2026-20353 and CVE-2026-76440 and 3 more CVEs affecting Cisco Secure Email and Web Manager.

cisco-sa-hardening-esa-dfCrfXkm Published Sep 14, 2026

CVE-2026-20353 CVE-2026-76440 CVE-2026-76441 CVE-2026-76442 CVE-2026-76443

Affected products & platforms

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Summary

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.

These vulnerabilities were found during internal testing. One of them is known to be actively exploited.

For more information, see Cisco Secure Email Gateway SQL Injection Vulnerability.

To assist customers in patching and streamline the disclosure process, Cisco has grouped these issues by their underlying vulnerability class — Common Weakness Enumeration (CWE) — and assigned a single Common Vulnerabilities and Exposures identifier (CVE ID) to each CWE grouping.

Cisco has released software updates that address these vulnerabilities. There are no workarounds that address these vulnerabilities.

Affected versions

No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.

Official advisory · high-confidence parse· fetched 2 hours ago·verify at source

Fixed versions

15.5.5-006
16.5.0-429

Official advisory · high-confidence parse· fetched 2 hours ago·verify at source

Mitigation checklist

Workaround status

There are no workarounds that address these vulnerabilities.

Official advisory · high-confidence parse· fetched 2 hours ago·verify at source

Sources

Official and corroborating records used to build this advisory.

Cisco Security Advisoriesofficial
Official vendor source used to discover this advisory; it remains the authority for affected products and remediation. Discovered from the machine-readable feed https://sec.cloudapps.cisco.com/security/center/psirtrss20/CiscoSecurityAdvisory.xml; this link opens the Cisco advisory index instead of the raw feed document.
Cisco
Official vendor advisoryofficial
Official advisory page fetched and parsed; accepted detail fields are attributed to this page.
Cisco
CVE.org CNA affected-product recordCVE.org
Structured CNA affected[] data independently confirmed the affected product scope; native advisory content remains authoritative.
CVE Program
CVE.org CNA affected-product recordCVE.org
Structured CNA affected[] data independently confirmed the affected product scope; native advisory content remains authoritative.
CVE Program
CVE.org CNA affected-product recordCVE.org
Structured CNA affected[] data independently confirmed the affected product scope; native advisory content remains authoritative.
CVE Program
CVE.org CNA affected-product recordCVE.org
Structured CNA affected[] data independently confirmed the affected product scope; native advisory content remains authoritative.
CVE Program
CVE.org CNA affected-product recordCVE.org
Structured CNA affected[] data independently confirmed the affected product scope; native advisory content remains authoritative.
CVE Program

Cross-references

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