All vulnerabilities
CVE-2026-20011

Multiple Cisco Products Snort 3 SMTP MIME Denial of Service Vulnerability

Cisco Cisco Open Source Snort3Network & edge
Open in ThreatlineRecord JSON
CVSS
5.8Medium
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.42%Chance of exploitation activity in the next 30 days, higher than 34% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed inNone listedNo source names a fixed version. Check the vendor advisory below
Published21 Oct 2026Updated 22 Oct 2026CVE List

What fixes it

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

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 2

1 outlet mention it. Reports are not confirmation; each links to its source.

Description

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.

Text from CVE List

Affected versions 90

  • Cisco Open Source Snort3affected: 3.1.2.0CVE List
  • Cisco Open Source Snort3affected: 3.1.3.0CVE List
  • Cisco Open Source Snort3affected: 3.1.4.0CVE List
  • Cisco Open Source Snort3affected: 3.1.5.0CVE List
  • Cisco Open Source Snort3affected: 3.1.6.0CVE List
  • Cisco Open Source Snort3affected: 3.1.7.0CVE List
  • Cisco Open Source Snort3affected: 3.1.8.0CVE List
  • Cisco Open Source Snort3affected: 3.1.9.0CVE List
  • Cisco Open Source Snort3affected: 3.1.10.0CVE List
  • Cisco Open Source Snort3affected: 3.1.12.0CVE List
  • Cisco Open Source Snort3affected: 3.1.13.0CVE List
  • Cisco Open Source Snort3affected: 3.1.14.0CVE List
  • Cisco Open Source Snort3affected: 3.1.15.0CVE List
  • Cisco Open Source Snort3affected: 3.1.16.0CVE List
  • Cisco Open Source Snort3affected: 3.1.17.0CVE List
  • Cisco Open Source Snort3affected: 3.1.18.0CVE List
  • Cisco Open Source Snort3affected: 3.1.19.0CVE List
  • Cisco Open Source Snort3affected: 3.1.20.0CVE List
  • Cisco Open Source Snort3affected: 3.1.21.0CVE List
  • Cisco Open Source Snort3affected: 3.1.22.0CVE List
  • Cisco Open Source Snort3affected: 3.1.23.0CVE List
  • Cisco Open Source Snort3affected: 3.1.24.0CVE List
  • Cisco Open Source Snort3affected: 3.1.25.0CVE List
  • Cisco Open Source Snort3affected: 3.1.27.0CVE List
  • Cisco Open Source Snort3affected: 3.1.28.0CVE List
  • Cisco Open Source Snort3affected: 3.1.29.0CVE List
  • Cisco Open Source Snort3affected: 3.1.30.0CVE List
  • Cisco Open Source Snort3affected: 3.1.31.0CVE List
  • Cisco Open Source Snort3affected: 3.1.32.0CVE List
  • Cisco Open Source Snort3affected: 3.1.36.0CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.0.0CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.0.0.1CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.0.1CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.0.1.1CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.0.2CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.2.0CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.0.2.1CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.0.3CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.2.0.1CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.0.4CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.2.1CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.0.5CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.3.0CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.2.2CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.2.3CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.3.1CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.2.4CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.0.6CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.2.5CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.2.4.1CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.3.1.1CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.4.0CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.0.6.1CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.2.5.1CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.4.1CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.2.6CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.0.6.2CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.4.1.1CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.2.7CVE List
  • Cisco Secure Firewall Threat Defense (FTD) Softwareaffected: 7.2.5.2CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 3.17.1SCVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 16.12.3CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: Fuji-16.9.5CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 16.12.4CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.3.1aCVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 16.6.6CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 16.12.2CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: Fuji-16.9.6CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 3.17.0SCVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: Fuji-16.9.3CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: Denali-16.3.7CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: Fuji-16.9.2CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: Fuji-16.9.4CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: Everest-16.6.4CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: Everest-16.6.3CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 16.6.5CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: Denali-16.3.5CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.2.1rCVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.1.1CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: Everest-16.6.2CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 16.6.7aCVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: Denali-16.3.4CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 16.6.1CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: Denali-16.3.9CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: Denali-16.3.3CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 16.12.1aCVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.3.2CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.4.1aCVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 16.12.5CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: Fuji-16.9.7CVE List

References 1