CVE-2026-20353

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreHIGH confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-09-14. a secondary CVSS source baseline 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.8Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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 v3
9.8
EG Score
9.8(high)
EG Risk
59(Track)
EG Risk 59/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
34%
KEV
Not listed

Published

September 14, 2026

Last Modified

September 15, 2026

Advisory Details (2)

Auto-updated Sep 15, 2026
⚠️ Active exploitation confirmed. No patch confirmed yet.
generic
https://www.cve.org/Media/News/item/blog/2026/06/16/Preserving-Vulnerability-Level-Identification
generic🔴 Active Exploitation

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

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-hardening-esa-dfCrfXkm

Vendor Advisories for CVE-2026-20353(2)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 47× in last 7d / 47× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-09-19 12:24 UTCGHSA enrichment
  2. 2026-09-19 08:22 UTCGHSA enrichment
  3. 2026-09-19 04:19 UTCGHSA enrichment
  4. 2026-09-19 00:15 UTCGHSA enrichment
  5. 2026-09-18 20:13 UTCEG score recompute
  6. 2026-09-18 20:13 UTCGHSA enrichment
  7. 2026-09-18 19:27 UTCEPSS rescore
  8. 2026-09-18 16:09 UTCGHSA enrichment
  9. 2026-09-18 12:00 UTCGHSA enrichment
  10. 2026-09-18 07:57 UTCGHSA enrichment
  11. 2026-09-18 03:54 UTCGHSA enrichment
  12. 2026-09-17 23:51 UTCGHSA enrichment
  13. 2026-09-17 19:33 UTCEG score recompute
  14. 2026-09-17 19:33 UTCGHSA enrichment
  15. 2026-09-17 15:11 UTCGHSA enrichment
  16. 2026-09-17 11:08 UTCGHSA enrichment
  17. 2026-09-17 07:05 UTCGHSA enrichment
  18. 2026-09-17 03:02 UTCGHSA enrichment
  19. 2026-09-16 22:59 UTCGHSA enrichment
  20. 2026-09-16 18:56 UTCGHSA enrichment
  21. 2026-09-16 14:52 UTCEG score recompute
  22. 2026-09-16 14:52 UTCGHSA enrichment
  23. 2026-09-16 14:07 UTCEPSS rescore
  24. 2026-09-16 10:47 UTCGHSA enrichment
  25. 2026-09-16 06:44 UTCEG score recompute
Show 22 more
  1. 2026-09-16 06:44 UTCGHSA enrichment
  2. 2026-09-16 05:15 UTCEPSS rescore
  3. 2026-09-16 02:42 UTCGHSA enrichment
  4. 2026-09-15 22:39 UTCGHSA enrichment
  5. 2026-09-15 18:35 UTCEG score recompute
  6. 2026-09-15 18:35 UTCGHSA enrichment
  7. 2026-09-15 17:23 UTCEG score recompute
  8. 2026-09-15 17:23 UTCGHSA enrichment
  9. 2026-09-15 16:36 UTCGHSA enrichment
  10. 2026-09-15 12:32 UTCGHSA enrichment
  11. 2026-09-15 08:28 UTCGHSA enrichment
  12. 2026-09-15 04:25 UTCEG score recompute
  13. 2026-09-15 04:25 UTCGHSA enrichment
  14. 2026-09-15 04:04 UTCEG score recompute
  15. 2026-09-15 04:04 UTCGHSA enrichment
  16. 2026-09-15 01:06 UTCGHSA enrichment
  17. 2026-09-14 21:03 UTCEG score recompute
  18. 2026-09-14 21:03 UTCGHSA enrichment
  19. 2026-09-14 17:27 UTCEG score recompute
  20. 2026-09-14 16:45 UTCEG score recompute
  21. 2026-09-14 16:20 UTCEG score recompute
  22. 2026-09-14 16:19 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-20353?
CVE-2026-20353 is a critical vulnerability published on September 14, 2026. 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…
When was CVE-2026-20353 disclosed?
CVE-2026-20353 was first published in the National Vulnerability Database on September 14, 2026, with the most recent update on September 15, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-20353 actively exploited?
CVE-2026-20353 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 66.4% of all scored CVEs.
What is the CVSS score of CVE-2026-20353?
CVE-2026-20353 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-20353?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-20353, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-20353

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