Answer in brief
CVE-2026-20011 records a Medium severity (CVSS 5.8) vulnerability in Multiple Cisco Products Snort 3 SMTP MIME Denial of Service Vulnerability. The current sources do not mark it as known exploited. The current feed maps 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 5.8. 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 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 Open Source Snort3generic | 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 || 3.7.4.0 || 3.9.0.0 || 3.5.2.0 || 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 || 3.9.1.0 | 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 | Not reported |
| Cisco/Cisco UTD SNORT IPS Engine Softwaregeneric | 3.17.1S || 16.12.3 || Fuji-16.9.5 || 16.12.4 || 17.3.1a || 16.6.6 || 16.12.2 || Fuji-16.9.6 || 3.17.0S || Fuji-16.9.3 || Denali-16.3.7 || Fuji-16.9.2 || Fuji-16.9.4 || Everest-16.6.4 || Everest-16.6.3 || 16.6.5 || Denali-16.3.5 || 17.2.1r || 17.1.1 || Everest-16.6.2 || 16.6.7a || Denali-16.3.4 || 16.6.1 || Denali-16.3.9 || Denali-16.3.3 || 16.12.1a || 17.3.2 || 17.4.1a || 16.12.5 || Fuji-16.9.7 || 16.6.9 || 17.3.3 || 17.5.1a || 17.3.4a || 17.4.2 || 17.4.1b || 17.6.1a || 16.6.10 || 17.7.1a || 16.12.6 || Fuji-16.9.8 || 17.6.2 || 17.8.1a || 16.12.7 || 17.3.5 || 17.6.3a || 17.7.2 || 17.9.1a || 17.6.4 || 17.10.1a || 17.3.6 || 16.12.8 || 17.3.7 || 17.9.2a || 17.6.5 || 17.11.1a || 17.9.3a || 17.12.1a || 17.9.4 || 17.6.6 || 17.3.8 || 17.12.2 || 17.13.1a || 17.9.5a || 17.12.3 || 17.6.7 || 17.14.1a || 17.12.4 || 17.12.3a || 17.15.1a || 17.9.6 || 17.6.8a || 17.16.1a || 17.9.5e || 17.12.4a || 17.15.2c || 17.9.5f || 17.12.4b || 17.15.2a || 17.12.5 || 17.17.1 || 17.12.5a || 17.9.7a || 17.15.3a || 17.15.3 || 17.12.5b || 17.12.5c || 17.15.4 || 17.9.7b || 17.18.1 || 17.18.1a || 17.12.6 || 17.9.8 || 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 || 17.9.9 || 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
Multiple Cisco products are affected by a vulnerability in the Snort 3 SMTP MIME Decoder that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart. This vulnerability is due to a lack of error checking when the MIME fields of the SMTP header are parsed. An attacker could exploit this vulnerability by sending crafted SMTP packets through an established connection to be parsed by Snort 3. A successful exploit could allow the attacker to cause a denial of service (DoS) condition when the Snort 3 Detection Engine unexpectedly restarts.
Quoted source text, attributed separately from HOL analysis.