CVE-2026-20197
Multiple Cisco Products Snort 3 Teredo Protocol Denial of Service Vulnerability
Published Oct 21, 2026
CVSS 3.1 · 5.8 Medium
EPSS < 1%
KEV · Not listed
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.
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
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CVE record
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NVD configurations
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Red Hat packages
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OpenCVE enrichment
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
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| Cisco | Cisco Open Source Snort3 | unknown |
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| Cisco | Cisco Secure Firewall Threat Defense (FTD) Software | unknown |
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| Cisco | Cisco UTD SNORT IPS Engine Software | unknown |
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No data.
No data.
| Vendor | Product | Versions | ||||||||
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| Cisco | Cisco Open Source Snort3 |
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| Cisco | Cisco Secure Firewall Threat Defense (ftd) Software |
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| Cisco | Cisco Utd Snort Ips Engine Software |
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| Cisco | Secure Firewall Threat Defense |
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Remediation
Tracking
Advisories
Metrics
No CVSS v4.0
Attack Vector Network
Attack Complexity Low
Privileges Required None
Scope Changed
Confidentiality Impact None
Integrity Impact None
Availability Impact Low
User Interaction None
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.495% probability within 30 days)
Exploitation none
Automatable yes
Technical Impact partial
References
History
Oct 22, 2026 2:30 PM
Scoring metrics updated
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| Type | Values Removed | Values Added |
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| Metrics |
ssvc
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Oct 22, 2026 9:30 AM
First appearance in the feed. Affected vendors updated
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| First Time appeared |
Cisco
Cisco cisco Open Source Snort3 Cisco cisco Secure Firewall Threat Defense (ftd) Software Cisco cisco Utd Snort Ips Engine Software Cisco secure Firewall Threat Defense |
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| Vendors & Products |
Cisco
Cisco cisco Open Source Snort3 Cisco cisco Secure Firewall Threat Defense (ftd) Software Cisco cisco Utd Snort Ips Engine Software Cisco secure Firewall Threat Defense |
Oct 21, 2026 5:15 PM
Description updated. Title updated. Weaknesses updated. Added references. Scoring metrics updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | Multiple Cisco Products Snort 3 Teredo Protocol Denial of Service Vulnerability | |
| Weaknesses | CWE-119 | |
| References |
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| Metrics |
cvssV3_1
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Subscriptions
Weaknesses
