Answer in brief
CVE-2026-20356 records a High severity (CVSS 7.5) vulnerability in Multiple Cisco Products Snort 3 Software Hardening Release: October 2026. The current sources do not mark it as known exploited. The current feed maps Cisco/Cisco Cyber Vision (generic), Cisco/Cisco Open Source Snort3 (generic), Cisco/Cisco Secure Firewall Threat Defense (FTD) Software (generic), Cisco/Cisco UTD SNORT IPS Engine Software (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Cisco/Cisco Cyber Vision (generic), Cisco/Cisco Open Source Snort3 (generic), Cisco/Cisco Secure Firewall Threat Defense (FTD) Software (generic), Cisco/Cisco UTD SNORT IPS Engine Software (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Cisco/Cisco Cyber Visiongeneric | 3.0.0 || 3.0.2 || 3.0.3 || 3.0.1 || 3.1.0 || 3.0.4 || 3.1.1 || 3.1.2 || 3.2.0 || 3.0.5 || 3.2.1 || 3.0.6 || 3.2.2 || 3.2.3 || 3.2.4 || 4.0.0 || 4.0.1 || 4.0.2 || 4.0.3 || 4.1.0 || 4.1.1 || 4.1.2 || 4.1.3 || 4.1.4 || 4.2.0 || 4.2.1 || 4.1.5 || 4.2.2 || 4.2.X || 4.2.3 || 4.2.4 || 4.2.6 || 4.1.6 || 4.3.0 || 4.3.1 || 4.3.2 || 4.3.3 || 4.4.0 || 4.4.1 || 4.4.2 || 4.4.3 || 4.1.7 || 5.0.0 || 5.0.1 || 5.0.2 || 5.1.0 || 5.1.1 || 5.1.2 || 5.1.3 || 5.2.0 || 5.2.1 || 5.3.0 || 5.3.1 || 5.3.2 || 5.3.3 || 5.5.1 || 5.6.1 || 5.4.0 || 5.4.1 || 5.4.2 || 5.7.0 || 5.8.1 || 5.7.1 || 5.8.0 || 5.5.2 | Not reported |
| Cisco/Cisco Open Source Snort3generic | 3.12.2.0 || 3.1.2.0 || 3.1.3.0 || 3.1.4.0 || 3.1.5.0 || 3.1.6.0 || 3.1.7.0 || 3.1.8.0 || 3.1.9.0 || 3.1.10.0 || 3.1.12.0 || 3.1.13.0 || 3.1.14.0 || 3.1.15.0 || 3.1.16.0 || 3.1.17.0 || 3.1.18.0 || 3.1.19.0 || 3.1.20.0 || 3.1.21.0 || 3.1.22.0 || 3.1.23.0 || 3.1.24.0 || 3.1.25.0 || 3.1.27.0 || 3.1.28.0 || 3.1.29.0 || 3.1.30.0 || 3.1.31.0 || 3.1.32.0 || 3.1.36.0 || 3.1.38.0 || 3.1.39.0 || 3.1.40.0 || 3.1.41.0 || 3.1.42.0 || 3.1.43.0 || 3.1.45.0 || 3.1.47.0 || 3.1.48.0 || 3.1.50.0 || 3.1.51.0 || 3.1.52.0 || 3.1.53.0 || 3.1.55.0 || 3.1.56.0 || 3.1.57.0 || 3.1.58.0 || 3.1.59.0 || 3.1.60.0 || 3.1.61.0 || 3.1.62.0 || 3.1.63.0 || 3.1.64.0 || 3.1.65.0 || 3.1.66.0 || 3.1.67.0 || 3.1.69.0 || 3.1.70.0 || 3.1.71.0 || 3.1.72.0 || 3.1.73.0 || 3.1.74.0 || 3.1.75.0 || 3.1.76.0 || 3.1.77.0 || 3.1.78.0 || 3.1.81.0 || 3.1.82.0 || 3.1.83.0 || 3.1.84.0 || 3.2.1.0 || 3.2.2.0 || 3.3.0.0 || 3.3.1.0 || 3.3.2.0 || 3.3.3.0 || 3.3.4.0 || 3.3.5.0 || 3.3.7.0 || 3.5.0.0 || 3.5.1.0 || 3.8.1.0 || 3.6.0.0 || 3.6.2.0 || 3.9.3.0 || 3.7.2.0 || 3.7.0.0 || 3.9.6.0 || 3.10.0.0 || 3.10.2.0 || 3.7.4.0 || 3.9.0.0 || 3.5.2.0 || 3.12.1.0 || 3.6.1.0 || 3.9.2.0 || 3.6.3.0 || 3.9.5.0 || 3.7.1.0 || 3.9.7.0 || 3.7.3.0 || 3.10.1.0 || 3.9.1.0 || 3.11.1.0 | Not reported |
| Cisco/Cisco Secure Firewall Threat Defense (FTD) Softwaregeneric | 7.0.0 || 7.0.0.1 || 7.0.1 || 7.0.1.1 || 7.0.2 || 7.2.0 || 7.0.2.1 || 7.0.3 || 7.2.0.1 || 7.0.4 || 7.2.1 || 7.0.5 || 7.3.0 || 7.2.2 || 7.2.3 || 7.3.1 || 7.2.4 || 7.0.6 || 7.2.5 || 7.2.4.1 || 7.3.1.1 || 7.4.0 || 7.0.6.1 || 7.2.5.1 || 7.4.1 || 7.2.6 || 7.0.6.2 || 7.4.1.1 || 7.2.7 || 7.2.5.2 || 7.3.1.2 || 7.2.8 || 7.6.0 || 7.4.2 || 7.2.8.1 || 7.0.6.3 || 7.4.2.1 || 7.2.9 || 7.0.7 || 7.7.0 || 7.4.2.2 || 7.2.10 || 7.6.1 || 7.4.2.3 || 7.0.8 || 7.6.2 || 7.7.10 || 7.7.11 || 7.0.8.1 || 7.6.2.1 || 7.7.10.1 || 7.4.2.4 || 7.2.10.2 || 7.4.3 || 7.6.4 || 10.0.0 || 7.4.4 || 7.0.9 || 7.2.11 || 7.4.7 | Not reported |
| Cisco/Cisco UTD SNORT IPS Engine Softwaregeneric | 17.12.1a || 17.12.2 || 17.13.1a || 17.12.3 || 17.14.1a || 17.12.4 || 17.12.3a || 17.15.1a || 17.16.1a || 17.12.4a || 17.15.2c || 17.12.4b || 17.15.2a || 17.12.5 || 17.17.1 || 17.12.5a || 17.15.3a || 17.15.3 || 17.12.5b || 17.12.5c || 17.15.4 || 17.18.1 || 17.18.1a || 17.12.6 || 17.15.4c || 17.12.5d || 17.18.2 || 26.1.1 || 17.15.5 || 17.15.5a || 17.12.7 || 17.12.7a || 17.12.7b || 17.18.3a || 17.12.8 || 17.15.6 || 17.18.4 || 26.1.2 | Not reported |
Published upstream
Oct 21, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 21, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Oct 21, 2026
As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco owned Open Source Snort 3 Software 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-2026-20356 are related to issues concerning uncontrolled resource consumption that are grouped under the Common Weakness Enumeration (CWE) Base CWE-400.
Quoted source text, attributed separately from HOL analysis.