CVE-2026-20197
Multiple Cisco Products Snort 3 Teredo Protocol Denial of Service Vulnerability
- Published
- Updated
- Reserved
- Assigned by
- cisco
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.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| ciscoCNA (assigner) | 3.1 | Medium5.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L |
| NVDNVD · Awaiting Analysis | 3.1 | Medium5.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L |
- EPSS (exploitation in 30 days)
- 0.50% · top 57% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.8.
Weakness
Affected products
Cisco · Cisco Open Source Snort3
- affected 3.12.2.0
- affected 3.1.2.0
- affected 3.1.3.0
- affected 3.1.4.0
- affected 3.1.5.0
- affected 3.1.6.0
- affected 3.1.7.0
- affected 3.1.8.0
- affected 3.1.9.0
- affected 3.1.10.0
- affected 3.1.12.0
- affected 3.1.13.0
- affected 3.1.14.0
- affected 3.1.15.0
- affected 3.1.16.0
- affected 3.1.17.0
- affected 3.1.18.0
- affected 3.1.19.0
- affected 3.1.20.0
- affected 3.1.21.0
- affected 3.1.22.0
- affected 3.1.23.0
- affected 3.1.24.0
- affected 3.1.25.0
- affected 3.1.27.0
- affected 3.1.28.0
- affected 3.1.29.0
- affected 3.1.30.0
- affected 3.1.31.0
- affected 3.1.32.0
- affected 3.1.36.0
- affected 3.1.38.0
- affected 3.1.39.0
- affected 3.1.40.0
- affected 3.1.41.0
- affected 3.1.42.0
- affected 3.1.43.0
- affected 3.1.45.0
- affected 3.1.47.0
- affected 3.1.48.0
- and 65 more
Cisco · Cisco Secure Firewall Threat Defense (FTD) Software
- affected 7.0.0
- affected 7.0.0.1
- affected 7.0.1
- affected 7.0.1.1
- affected 7.0.2
- affected 7.2.0
- affected 7.0.2.1
- affected 7.0.3
- affected 7.2.0.1
- affected 7.0.4
- affected 7.2.1
- affected 7.0.5
- affected 7.3.0
- affected 7.2.2
- affected 7.2.3
- affected 7.3.1
- affected 7.2.4
- affected 7.0.6
- affected 7.2.5
- affected 7.2.4.1
- affected 7.3.1.1
- affected 7.4.0
- affected 7.0.6.1
- affected 7.2.5.1
- affected 7.4.1
- affected 7.2.6
- affected 7.0.6.2
- affected 7.4.1.1
- affected 7.2.7
- affected 7.2.5.2
- affected 7.3.1.2
- affected 7.2.8
- affected 7.6.0
- affected 7.4.2
- affected 7.2.8.1
- affected 7.0.6.3
- affected 7.4.2.1
- affected 7.2.9
- affected 7.0.7
- affected 7.7.0
- and 20 more
Cisco · Cisco UTD SNORT IPS Engine Software
- affected 17.12.1a
- affected 17.12.2
- affected 17.13.1a
- affected 17.12.3
- affected 17.14.1a
- affected 17.12.4
- affected 17.12.3a
- affected 17.15.1a
- affected 17.16.1a
- affected 17.12.4a
- affected 17.15.2c
- affected 17.12.4b
- affected 17.15.2a
- affected 17.12.5
- affected 17.17.1
- affected 17.12.5a
- affected 17.15.3a
- affected 17.15.3
- affected 17.12.5b
- affected 17.12.5c
- affected 17.15.4
- affected 17.18.1
- affected 17.18.1a
- affected 17.12.6
- affected 17.15.4c
- affected 17.12.5d
- affected 17.18.2
- affected 26.1.1
- affected 17.15.5
- affected 17.15.5a
- affected 17.12.7
- affected 17.12.7a
- affected 17.12.7b
- affected 17.18.3a
- affected 17.12.8
- affected 17.15.6
- affected 17.18.4
- affected 26.1.2
What to do
Exploitation: The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerabilities that are described in this advisory.
References (1)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-20197)Record last updated .