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CVE-2026-20197: Multiple Cisco Products Snort 3 Teredo Protocol Denial of Service Vulnerability
- Severity: medium (CVSS 5.8 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.5% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-10-21 · updated 2026-10-22
- Weakness: CWE-119
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
- Cisco Open Source Snort3: 3.12.2.0, 3.1.2.0, 3.1.3.0, 3.1.4.0, 3.1.5.0, 3.1.6.0 (+99)
- Cisco Firepower Threat Defense Software: 7.0.0, 7.0.0.1, 7.0.1, 7.0.1.1, 7.0.2, 7.2.0 (+54)
- Cisco UTD SNORT IPS Engine Software: 17.12.1a, 17.12.2, 17.13.1a, 17.12.3, 17.14.1a, 17.12.4 (+32)
In the news
- Multiple Cisco Products Snort 3 Denial of Service Vulnerabilities
- Cisco Advance Notification for Publication of October 21, 2026, Security Advisories
References
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