A vulnerability in SSL/TLS certificate parsing in the Snort 2 Detection Engine of Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the Snort 2 Detection Engine to restart. This vulnerability is due to incomplete validation of the SSL certificate. An attacker could exploit this vulnerability by sending a crafted SSL connection setup request to be parsed by Snort 2. A successful exploit could allow the attacker to cause the Snort 2 Detection Engine to restart unexpectedly, resulting in a denial of service (DoS) condition.
CVE-2026-20290
MEDIUMPre-NVD 5.85.8—Trending — 4 sources updated this week
EchelonGraph scoreHIGH confidence
Score 5.8 from GitHub Security Advisory published 2026-09-16. a secondary CVSS source baseline 5.8; sources differ by 0.0.
Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
5.8EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
- Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.8Exploit: None knownExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 5.8
- EG Score
- 5.8(high)
- EG Risk
- 31(Track)EG Risk 31/100SSVC: 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 computedSeverity58% × 45%Exploitation0% × 40%Automatability30% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- 0%
- EPSS %ILE
- 9%
- KEV
- Not listed
Published
September 16, 2026
Last Modified
September 18, 2026
Advisory Details (1)
Auto-updated Sep 16, 2026No patch confirmed yet.
generic
Cisco Secure Firewall Threat Defense Software Snort 2 SSL/TLS Denial of Service Vulnerability
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-snort2-ssldos-Mw7WYX9cVendor Advisories for CVE-2026-20290(2)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
- GHSA-xxfc-5fpg-3fhqGitHub Security AdvisoriesMedium
A vulnerability in SSL/TLS certificate parsing in the Snort 2 Detection Engine of Cisco Secure...
- cisco-sa-ftd-snort2-ssldos-Mw7WYX9cCisco PSIRT openVulnMedium
Cisco Secure Firewall Threat Defense Software Snort 2 SSL/TLS Denial of Service Vulnerability
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 8× in last 7d / 8× 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.
- 2026-09-18 19:27 UTCEPSS rescore
- 2026-09-18 13:41 UTCEG score recompute
- 2026-09-18 13:41 UTCGHSA enrichment
- 2026-09-17 18:26 UTCEG score recompute
- 2026-09-17 18:26 UTCGHSA enrichment
- 2026-09-16 21:26 UTCEG score recompute
- 2026-09-16 20:33 UTCEG score recompute
- 2026-09-16 20:29 UTCMITRE cvelistV5first tracked
Frequently asked(5)
What is CVE-2026-20290?
CVE-2026-20290 is a medium vulnerability published on September 16, 2026. A vulnerability in SSL/TLS certificate parsing in the Snort 2 Detection Engine of Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the Snort 2 Detection Engine to restart. This vulnerability is due to incomplete validation of the SSL…
When was CVE-2026-20290 disclosed?
CVE-2026-20290 was first published in the National Vulnerability Database on September 16, 2026, with the most recent update on September 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-20290 actively exploited?
CVE-2026-20290 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 91.1% of all scored CVEs.
What is the CVSS score of CVE-2026-20290?
CVE-2026-20290 has a CVSS v3 base score of 5.8 (NVD).
How do I remediate CVE-2026-20290?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-20290, 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-2026-20290
Is Your Infrastructure Affected by CVE-2026-20290?
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