Vulnerability · Published Oct 21, 2026 · Assigned by cisco
CVE-2026-20197Multiple Cisco Products Snort 3 Teredo Protocol Denial of Service Vulnerability
Medium 5.8
In plain English
A medium-severity memory corruption in Cisco Open Source Snort3 from Cisco. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 43% of all known vulnerabilities).
Official 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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Cisco | Cisco Open Source Snort3 | 3.12.2.03.1.2.03.1.3.03.1.4.03.1.5.03.1.6.03.1.7.03.1.8.0 |
| Cisco | Cisco Secure Firewall Threat Defense (FTD) Software | 7.0.07.0.0.17.0.17.0.1.17.0.27.2.07.0.2.17.0.3 |
| Cisco | Cisco UTD SNORT IPS Engine Software | 17.12.1a17.12.217.13.1a17.12.317.14.1a17.12.417.12.3a17.15.1a |
Weakness: CWE-119 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L