All vulnerabilities
CVE-2026-20353

Cisco Secure Email Gateway Security Hardening Release

Cisco Cisco Secure EmailNetwork & edge
Open in ThreatlineRecord JSON
CVSS
9.8Critical
ExploitationExploitation reported1 outlet report it, first 14 Oct 2026. Not yet in the KEV catalogReports
Exploit odds (EPSS)0.40%Chance of exploitation activity in the next 30 days, higher than 32% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed inNone listedNo source names a fixed version. Check the vendor advisory below
Published14 Sep 2026Updated 15 Sep 2026CVE List

What fixes it

No source in this snapshot names a fixed version. The vendor advisories under References are the place to check.

Timeline

  1. 14 Sep 2026, 16:08 UTCPublishedCVE List
  2. 14 Oct 2026, 16:00 UTCFirst reported exploitedCisco PSIRT
  3. NowNot on CISA's known exploited list yet

Vendor and government advisories 1

Vendors that say their products are affected, and agencies that issued alerts. Check each for the fixed release of the product you run.

Reports 1

One outlet reports exploitation. Reports are not confirmation; each links to its source.

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.

Text from CVE List

Affected versions 23

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

References 2