All vulnerabilities
CVE-2026-20197

Multiple Cisco Products Snort 3 Teredo Protocol 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)0.39%Chance of exploitation activity in the next 30 days, higher than 31% 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 Teredo Detection Engine that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart, resulting in an interruption of packet inspection.

This vulnerability is due to incomplete error checking when Snort 3 parses Teredo packets. An attacker could exploit this vulnerability by sending a crafted Teredo packet to a targeted device to be parsed by Snort. A successful exploit could allow the attacker to cause the Snort 3 Detection Engine to restart unexpectedly, resulting in a DoS condition.

Text from CVE List

Affected versions 90

  • Cisco Open Source Snort3affected: 3.12.2.0CVE List
  • 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 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: 17.12.1aCVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.12.2CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.13.1aCVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.12.3CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.14.1aCVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.12.4CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.12.3aCVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.15.1aCVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.16.1aCVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.12.4aCVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.15.2cCVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.12.4bCVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.15.2aCVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.12.5CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.17.1CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.12.5aCVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.15.3aCVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.15.3CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.12.5bCVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.12.5cCVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.15.4CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.18.1CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.18.1aCVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.12.6CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.15.4cCVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.12.5dCVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.18.2CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 26.1.1CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.15.5CVE List
  • Cisco UTD SNORT IPS Engine Softwareaffected: 17.15.5aCVE List

References 1