CVE-2026-20221 (GCVE-0-2026-20221)
Vulnerability from cvelistv5 – Published: 2026-10-21 16:12 – Updated: 2026-10-22 13:37
VLAI
EPSS
VEX
Title
Multiple Cisco Products Snort 3 Generic Routing Encapsulation Denial of Service Vulnerabilities
Summary
Multiple Cisco products are affected by a vulnerability in the generic routing encapsulation (GRE) tunnel decapsulation feature of the Snort 3 Detection Engine that could allow an unauthenticated, remote attacker to cause an unexpected restart of the Snort 3 Detection Engine.
This vulnerability is due to improper handling of nested GRE traffic. An attacker could exploit this vulnerability by sending a crafted GRE payload through an affected device. A successful exploit could allow the attacker to trigger an unexpected reload of the Snort 3 Detection Engine, resulting in either a bypass or denial of service (DoS) condition, depending on device configuration. For more information, see the section of this advisory. The Snort 3 Detection Engine will restart automatically. No manual intervention is required.
Severity
5.8 (Medium)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-22 13:23 UTC
CWE
- CWE-476 - NULL Pointer Dereference
Assigner
References
1 reference
Impacted products
5 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Cisco | Cisco Cyber Vision |
Affected:
3.0.0
Affected: 3.0.2 Affected: 3.0.3 Affected: 3.0.1 Affected: 3.1.0 Affected: 3.0.4 Affected: 3.1.1 Affected: 3.1.2 Affected: 3.2.0 Affected: 3.0.5 Affected: 3.2.1 Affected: 3.0.6 Affected: 3.2.2 Affected: 3.2.3 Affected: 3.2.4 Affected: 4.0.0 Affected: 4.0.1 Affected: 4.0.2 Affected: 4.0.3 Affected: 4.1.0 Affected: 4.1.1 Affected: 4.1.2 Affected: 4.1.3 Affected: 4.1.4 Affected: 4.2.0 Affected: 4.2.1 Affected: 4.1.5 Affected: 4.2.2 Affected: 4.2.X Affected: 4.2.3 Affected: 4.2.4 Affected: 4.2.6 Affected: 4.1.6 Affected: 4.3.0 Affected: 4.3.1 Affected: 4.3.2 Affected: 4.3.3 Affected: 4.4.0 Affected: 4.4.1 Affected: 4.4.2 Affected: 4.4.3 Affected: 4.1.7 Affected: 5.0.0 Affected: 5.0.1 Affected: 5.0.2 Affected: 5.1.0 Affected: 5.1.1 Affected: 5.1.2 Affected: 5.1.3 Affected: 5.2.0 Affected: 5.2.1 Affected: 5.3.0 Affected: 5.3.1 Affected: 5.3.2 Affected: 5.3.3 Affected: 5.5.1 Affected: 5.6.1 Affected: 5.6.0 Affected: 5.4.0 Affected: 5.4.1 Affected: 5.4.2 |
guessed | |
| 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 Affected: 3.1.50.0 Affected: 3.1.51.0 Affected: 3.1.52.0 Affected: 3.1.53.0 Affected: 3.1.55.0 Affected: 3.1.56.0 Affected: 3.1.57.0 Affected: 3.1.58.0 Affected: 3.1.59.0 Affected: 3.1.60.0 Affected: 3.1.61.0 Affected: 3.1.62.0 Affected: 3.1.63.0 Affected: 3.1.64.0 Affected: 3.1.65.0 Affected: 3.1.66.0 Affected: 3.1.67.0 Affected: 3.1.69.0 Affected: 3.1.70.0 Affected: 3.1.71.0 Affected: 3.1.72.0 Affected: 3.1.73.0 Affected: 3.1.74.0 Affected: 3.1.75.0 Affected: 3.1.76.0 Affected: 3.1.77.0 Affected: 3.1.78.0 Affected: 3.1.81.0 Affected: 3.1.82.0 Affected: 3.1.83.0 Affected: 3.1.84.0 Affected: 3.2.1.0 Affected: 3.2.2.0 Affected: 3.3.0.0 Affected: 3.3.1.0 Affected: 3.3.2.0 Affected: 3.3.3.0 Affected: 3.3.4.0 Affected: 3.3.5.0 Affected: 3.3.7.0 Affected: 3.5.0.0 Affected: 3.5.1.0 Affected: 3.8.1.0 Affected: 3.6.0.0 Affected: 3.6.2.0 Affected: 3.9.3.0 Affected: 3.7.2.0 Affected: 3.7.0.0 Affected: 3.9.6.0 Affected: 3.10.0.0 Affected: 3.10.2.0 Affected: 3.7.4.0 Affected: 3.9.0.0 Affected: 3.5.2.0 Affected: 3.12.1.0 Affected: 3.6.1.0 Affected: 3.9.2.0 Affected: 3.6.3.0 Affected: 3.9.5.0 Affected: 3.7.1.0 Affected: 3.9.7.0 Affected: 3.7.3.0 Affected: 3.10.1.0 Affected: 3.9.1.0 Affected: 3.11.1.0 |
guessed | |
| 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 Affected: 7.4.2.2 Affected: 7.2.10 Affected: 7.6.1 Affected: 7.4.2.3 Affected: 7.0.8 Affected: 7.6.2 Affected: 7.7.10 Affected: 7.7.11 Affected: 7.0.8.1 Affected: 7.6.2.1 Affected: 7.7.10.1 Affected: 7.4.2.4 Affected: 7.2.10.2 Affected: 7.4.3 Affected: 7.6.4 Affected: 10.0.0 Affected: 7.4.4 Affected: 7.0.9 Affected: 7.2.11 Affected: 7.4.7 |
guessed | |
| Cisco | Cisco Umbrella Insights Virtual Appliance |
Affected:
2.6.0
Affected: 2.5.6 Affected: 2.5 Affected: 2.4.12 Affected: 2.7 Affected: 2.6.2 Affected: 2.5.5 Affected: 2.5.4 Affected: 2.8 Affected: 2.6.1 Affected: 2.5.7 Affected: 1.5.4 Affected: 1.5.5 Affected: 1.5.6 Affected: 2.0.0 Affected: 2.0.2 Affected: 2.0.3 Affected: 2.1.0 Affected: 2.1.2 Affected: 2.1.4 Affected: 2.1.5 Affected: 2.2 Affected: 2.2.1 Affected: 2.3 Affected: 2.3.1 Affected: 2.4 Affected: 2.4.4 Affected: 2.4.6 Affected: 2.8.9 Affected: 3.0 Affected: 3.1 Affected: 3.2 Affected: 2.8.1 Affected: 2.8.2 Affected: 2.8.3 Affected: 2.8.4 Affected: 2.8.5 Affected: 3.0.1 Affected: 3.0.2 Affected: 3.0.4 Affected: 3.0.5 Affected: 3.1.1 Affected: 3.1.2 Affected: 3.1.3 Affected: 3.1.4 Affected: 3.2.1 Affected: 3.2.2 Affected: 3.2.3 Affected: 3.3 Affected: 3.3.1 Affected: 3.3.2 Affected: 3.3.3 Affected: 3.3.4 Affected: 3.4 Affected: 3.4.1 Affected: 3.4.2 Affected: 3.4.3 Affected: 3.4.4 Affected: 3.4.5 Affected: 3.4.6 Affected: 3.5 Affected: 2.7.1 Affected: 2.7.2 Affected: 2.7.6 Affected: 2.7.9 Affected: 2.7.10 Affected: 3.5.1 Affected: 3.5.2 Affected: 3.6.1 Affected: 3.6.2 Affected: 3.7 Affected: 3.7.1 Affected: 3.8.3 |
guessed | |
| Cisco | Cisco UTD SNORT IPS Engine Software |
Affected:
3.17.1S
Affected: 16.12.3 Affected: Fuji-16.9.5 Affected: 16.12.4 Affected: 17.3.1a Affected: 16.6.6 Affected: 16.12.2 Affected: Fuji-16.9.6 Affected: 3.17.0S Affected: Fuji-16.9.3 Affected: Denali-16.3.7 Affected: Fuji-16.9.2 Affected: Fuji-16.9.4 Affected: Everest-16.6.4 Affected: Everest-16.6.3 Affected: 16.6.5 Affected: Denali-16.3.5 Affected: 17.2.1r Affected: 17.1.1 Affected: Everest-16.6.2 Affected: 16.6.7a Affected: Denali-16.3.4 Affected: 16.6.1 Affected: Denali-16.3.9 Affected: Denali-16.3.3 Affected: 16.12.1a Affected: 17.3.2 Affected: 17.4.1a Affected: 16.12.5 Affected: 17.5.1 Affected: Fuji-16.9.7 Affected: 16.6.9 Affected: 17.3.3 Affected: 17.5.1a Affected: 17.3.4 Affected: 17.3.4a Affected: 17.4.2 Affected: 17.4.1b Affected: 17.6.1a Affected: 16.6.10 Affected: 17.7.1a Affected: 16.12.6 Affected: Fuji-16.9.8 Affected: 17.6.2 Affected: 17.8.1a Affected: 16.12.7 Affected: 17.3.5 Affected: 17.6.3 Affected: 17.6.3a Affected: 17.7.2 Affected: 17.9.1a Affected: 17.6.4 Affected: 17.10.1a Affected: 17.3.6 Affected: 16.12.8 Affected: 17.3.7 Affected: 17.9.2a Affected: 17.6.5 Affected: 17.11.1a Affected: 17.9.3a Affected: 17.12.1a Affected: 17.9.4 Affected: 17.6.6 Affected: 17.3.8 Affected: 17.3.8a Affected: 17.6.6a Affected: 17.9.4a Affected: 17.12.2 Affected: 17.13.1a Affected: 17.9.5a Affected: 17.12.3 Affected: 17.6.7 Affected: 17.14.1a Affected: 17.12.4 Affected: 17.12.3a Affected: 17.15.1a Affected: 17.6.8 Affected: 17.9.6 Affected: 17.6.8a Affected: 17.16.1a Affected: 17.9.5e Affected: 17.12.4a Affected: 17.15.2c Affected: 17.9.5f Affected: 17.12.4b Affected: 17.15.2a Affected: 17.12.5 Affected: 17.17.1 Affected: 17.12.5a Affected: 17.9.7a Affected: 17.15.3a Affected: 17.15.3 Affected: 17.12.5b Affected: 17.12.5c Affected: 17.15.4 Affected: 17.9.7b Affected: 17.18.1 Affected: 17.18.1a Affected: 17.12.6 Affected: 17.9.8 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: 17.9.9 Affected: 17.18.3a Affected: 17.12.8 Affected: 17.15.6 Affected: 17.18.4 Affected: 26.1.2 Affected: 17.9.10 |
guessed |
{
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-20221",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "yes"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-10-22T13:23:54.810399Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-10-22T13:37:55.375Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"defaultStatus": "unknown",
"product": "Cisco Cyber Vision",
"vendor": "Cisco",
"versions": [
{
"status": "affected",
"version": "3.0.0"
},
{
"status": "affected",
"version": "3.0.2"
},
{
"status": "affected",
"version": "3.0.3"
},
{
"status": "affected",
"version": "3.0.1"
},
{
"status": "affected",
"version": "3.1.0"
},
{
"status": "affected",
"version": "3.0.4"
},
{
"status": "affected",
"version": "3.1.1"
},
{
"status": "affected",
"version": "3.1.2"
},
{
"status": "affected",
"version": "3.2.0"
},
{
"status": "affected",
"version": "3.0.5"
},
{
"status": "affected",
"version": "3.2.1"
},
{
"status": "affected",
"version": "3.0.6"
},
{
"status": "affected",
"version": "3.2.2"
},
{
"status": "affected",
"version": "3.2.3"
},
{
"status": "affected",
"version": "3.2.4"
},
{
"status": "affected",
"version": "4.0.0"
},
{
"status": "affected",
"version": "4.0.1"
},
{
"status": "affected",
"version": "4.0.2"
},
{
"status": "affected",
"version": "4.0.3"
},
{
"status": "affected",
"version": "4.1.0"
},
{
"status": "affected",
"version": "4.1.1"
},
{
"status": "affected",
"version": "4.1.2"
},
{
"status": "affected",
"version": "4.1.3"
},
{
"status": "affected",
"version": "4.1.4"
},
{
"status": "affected",
"version": "4.2.0"
},
{
"status": "affected",
"version": "4.2.1"
},
{
"status": "affected",
"version": "4.1.5"
},
{
"status": "affected",
"version": "4.2.2"
},
{
"status": "affected",
"version": "4.2.X"
},
{
"status": "affected",
"version": "4.2.3"
},
{
"status": "affected",
"version": "4.2.4"
},
{
"status": "affected",
"version": "4.2.6"
},
{
"status": "affected",
"version": "4.1.6"
},
{
"status": "affected",
"version": "4.3.0"
},
{
"status": "affected",
"version": "4.3.1"
},
{
"status": "affected",
"version": "4.3.2"
},
{
"status": "affected",
"version": "4.3.3"
},
{
"status": "affected",
"version": "4.4.0"
},
{
"status": "affected",
"version": "4.4.1"
},
{
"status": "affected",
"version": "4.4.2"
},
{
"status": "affected",
"version": "4.4.3"
},
{
"status": "affected",
"version": "4.1.7"
},
{
"status": "affected",
"version": "5.0.0"
},
{
"status": "affected",
"version": "5.0.1"
},
{
"status": "affected",
"version": "5.0.2"
},
{
"status": "affected",
"version": "5.1.0"
},
{
"status": "affected",
"version": "5.1.1"
},
{
"status": "affected",
"version": "5.1.2"
},
{
"status": "affected",
"version": "5.1.3"
},
{
"status": "affected",
"version": "5.2.0"
},
{
"status": "affected",
"version": "5.2.1"
},
{
"status": "affected",
"version": "5.3.0"
},
{
"status": "affected",
"version": "5.3.1"
},
{
"status": "affected",
"version": "5.3.2"
},
{
"status": "affected",
"version": "5.3.3"
},
{
"status": "affected",
"version": "5.5.1"
},
{
"status": "affected",
"version": "5.6.1"
},
{
"status": "affected",
"version": "5.6.0"
},
{
"status": "affected",
"version": "5.4.0"
},
{
"status": "affected",
"version": "5.4.1"
},
{
"status": "affected",
"version": "5.4.2"
}
]
},
{
"defaultStatus": "unknown",
"product": "Cisco Open Source Snort3",
"vendor": "Cisco",
"versions": [
{
"status": "affected",
"version": "3.12.2.0"
},
{
"status": "affected",
"version": "3.1.2.0"
},
{
"status": "affected",
"version": "3.1.3.0"
},
{
"status": "affected",
"version": "3.1.4.0"
},
{
"status": "affected",
"version": "3.1.5.0"
},
{
"status": "affected",
"version": "3.1.6.0"
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{
"status": "affected",
"version": "3.1.7.0"
},
{
"status": "affected",
"version": "3.1.8.0"
},
{
"status": "affected",
"version": "3.1.9.0"
},
{
"status": "affected",
"version": "3.1.10.0"
},
{
"status": "affected",
"version": "3.1.12.0"
},
{
"status": "affected",
"version": "3.1.13.0"
},
{
"status": "affected",
"version": "3.1.14.0"
},
{
"status": "affected",
"version": "3.1.15.0"
},
{
"status": "affected",
"version": "3.1.16.0"
},
{
"status": "affected",
"version": "3.1.17.0"
},
{
"status": "affected",
"version": "3.1.18.0"
},
{
"status": "affected",
"version": "3.1.19.0"
},
{
"status": "affected",
"version": "3.1.20.0"
},
{
"status": "affected",
"version": "3.1.21.0"
},
{
"status": "affected",
"version": "3.1.22.0"
},
{
"status": "affected",
"version": "3.1.23.0"
},
{
"status": "affected",
"version": "3.1.24.0"
},
{
"status": "affected",
"version": "3.1.25.0"
},
{
"status": "affected",
"version": "3.1.27.0"
},
{
"status": "affected",
"version": "3.1.28.0"
},
{
"status": "affected",
"version": "3.1.29.0"
},
{
"status": "affected",
"version": "3.1.30.0"
},
{
"status": "affected",
"version": "3.1.31.0"
},
{
"status": "affected",
"version": "3.1.32.0"
},
{
"status": "affected",
"version": "3.1.36.0"
},
{
"status": "affected",
"version": "3.1.38.0"
},
{
"status": "affected",
"version": "3.1.39.0"
},
{
"status": "affected",
"version": "3.1.40.0"
},
{
"status": "affected",
"version": "3.1.41.0"
},
{
"status": "affected",
"version": "3.1.42.0"
},
{
"status": "affected",
"version": "3.1.43.0"
},
{
"status": "affected",
"version": "3.1.45.0"
},
{
"status": "affected",
"version": "3.1.47.0"
},
{
"status": "affected",
"version": "3.1.48.0"
},
{
"status": "affected",
"version": "3.1.50.0"
},
{
"status": "affected",
"version": "3.1.51.0"
},
{
"status": "affected",
"version": "3.1.52.0"
},
{
"status": "affected",
"version": "3.1.53.0"
},
{
"status": "affected",
"version": "3.1.55.0"
},
{
"status": "affected",
"version": "3.1.56.0"
},
{
"status": "affected",
"version": "3.1.57.0"
},
{
"status": "affected",
"version": "3.1.58.0"
},
{
"status": "affected",
"version": "3.1.59.0"
},
{
"status": "affected",
"version": "3.1.60.0"
},
{
"status": "affected",
"version": "3.1.61.0"
},
{
"status": "affected",
"version": "3.1.62.0"
},
{
"status": "affected",
"version": "3.1.63.0"
},
{
"status": "affected",
"version": "3.1.64.0"
},
{
"status": "affected",
"version": "3.1.65.0"
},
{
"status": "affected",
"version": "3.1.66.0"
},
{
"status": "affected",
"version": "3.1.67.0"
},
{
"status": "affected",
"version": "3.1.69.0"
},
{
"status": "affected",
"version": "3.1.70.0"
},
{
"status": "affected",
"version": "3.1.71.0"
},
{
"status": "affected",
"version": "3.1.72.0"
},
{
"status": "affected",
"version": "3.1.73.0"
},
{
"status": "affected",
"version": "3.1.74.0"
},
{
"status": "affected",
"version": "3.1.75.0"
},
{
"status": "affected",
"version": "3.1.76.0"
},
{
"status": "affected",
"version": "3.1.77.0"
},
{
"status": "affected",
"version": "3.1.78.0"
},
{
"status": "affected",
"version": "3.1.81.0"
},
{
"status": "affected",
"version": "3.1.82.0"
},
{
"status": "affected",
"version": "3.1.83.0"
},
{
"status": "affected",
"version": "3.1.84.0"
},
{
"status": "affected",
"version": "3.2.1.0"
},
{
"status": "affected",
"version": "3.2.2.0"
},
{
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"descriptions": [
{
"lang": "en",
"value": "Multiple Cisco products are affected by a vulnerability in the generic routing encapsulation (GRE) tunnel decapsulation feature of the Snort 3 Detection Engine that could allow an unauthenticated, remote attacker to cause an unexpected restart of the Snort 3 Detection Engine.\r\n\r\nThis vulnerability is due to improper handling of nested GRE traffic. An attacker could exploit this vulnerability by sending a crafted GRE payload through an affected device. A successful exploit could allow the attacker to trigger an unexpected reload of the Snort 3 Detection Engine, resulting in either a bypass or denial of service (DoS) condition, depending on device configuration. For more information, see the section of this advisory. The Snort 3 Detection Engine will restart automatically. No manual intervention is required."
}
],
"exploits": [
{
"lang": "en",
"value": "The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory."
}
],
"metrics": [
{
"cvssV3_1": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "LOW",
"baseScore": 5.8,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "CHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L",
"version": "3.1"
},
"format": "cvssV3_1"
}
],
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{
"descriptions": [
{
"cweId": "CWE-476",
"description": "NULL Pointer Dereference",
"lang": "en",
"type": "cwe"
}
]
}
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"orgId": "d1c1063e-7a18-46af-9102-31f8928bc633",
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"name": "cisco-sa-snort3-gre-JNpMHrTv",
"url": "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snort3-gre-JNpMHrTv"
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"title": "Multiple Cisco Products Snort 3 Generic Routing Encapsulation Denial of Service Vulnerabilities"
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"version": "3.3.3"
},
{
"status": "affected",
"version": "3.3.4"
},
{
"status": "affected",
"version": "3.4"
},
{
"status": "affected",
"version": "3.4.1"
},
{
"status": "affected",
"version": "3.4.2"
},
{
"status": "affected",
"version": "3.4.3"
},
{
"status": "affected",
"version": "3.4.4"
},
{
"status": "affected",
"version": "3.4.5"
},
{
"status": "affected",
"version": "3.4.6"
},
{
"status": "affected",
"version": "3.5"
},
{
"status": "affected",
"version": "2.7.1"
},
{
"status": "affected",
"version": "2.7.2"
},
{
"status": "affected",
"version": "2.7.6"
},
{
"status": "affected",
"version": "2.7.9"
},
{
"status": "affected",
"version": "2.7.10"
},
{
"status": "affected",
"version": "3.5.1"
},
{
"status": "affected",
"version": "3.5.2"
},
{
"status": "affected",
"version": "3.6.1"
},
{
"status": "affected",
"version": "3.6.2"
},
{
"status": "affected",
"version": "3.7"
},
{
"status": "affected",
"version": "3.7.1"
},
{
"status": "affected",
"version": "3.8.3"
}
]
},
{
"defaultStatus": "unknown",
"product": "Cisco UTD SNORT IPS Engine Software",
"vendor": "Cisco",
"versions": [
{
"status": "affected",
"version": "3.17.1S"
},
{
"status": "affected",
"version": "16.12.3"
},
{
"status": "affected",
"version": "Fuji-16.9.5"
},
{
"status": "affected",
"version": "16.12.4"
},
{
"status": "affected",
"version": "17.3.1a"
},
{
"status": "affected",
"version": "16.6.6"
},
{
"status": "affected",
"version": "16.12.2"
},
{
"status": "affected",
"version": "Fuji-16.9.6"
},
{
"status": "affected",
"version": "3.17.0S"
},
{
"status": "affected",
"version": "Fuji-16.9.3"
},
{
"status": "affected",
"version": "Denali-16.3.7"
},
{
"status": "affected",
"version": "Fuji-16.9.2"
},
{
"status": "affected",
"version": "Fuji-16.9.4"
},
{
"status": "affected",
"version": "Everest-16.6.4"
},
{
"status": "affected",
"version": "Everest-16.6.3"
},
{
"status": "affected",
"version": "16.6.5"
},
{
"status": "affected",
"version": "Denali-16.3.5"
},
{
"status": "affected",
"version": "17.2.1r"
},
{
"status": "affected",
"version": "17.1.1"
},
{
"status": "affected",
"version": "Everest-16.6.2"
},
{
"status": "affected",
"version": "16.6.7a"
},
{
"status": "affected",
"version": "Denali-16.3.4"
},
{
"status": "affected",
"version": "16.6.1"
},
{
"status": "affected",
"version": "Denali-16.3.9"
},
{
"status": "affected",
"version": "Denali-16.3.3"
},
{
"status": "affected",
"version": "16.12.1a"
},
{
"status": "affected",
"version": "17.3.2"
},
{
"status": "affected",
"version": "17.4.1a"
},
{
"status": "affected",
"version": "16.12.5"
},
{
"status": "affected",
"version": "17.5.1"
},
{
"status": "affected",
"version": "Fuji-16.9.7"
},
{
"status": "affected",
"version": "16.6.9"
},
{
"status": "affected",
"version": "17.3.3"
},
{
"status": "affected",
"version": "17.5.1a"
},
{
"status": "affected",
"version": "17.3.4"
},
{
"status": "affected",
"version": "17.3.4a"
},
{
"status": "affected",
"version": "17.4.2"
},
{
"status": "affected",
"version": "17.4.1b"
},
{
"status": "affected",
"version": "17.6.1a"
},
{
"status": "affected",
"version": "16.6.10"
},
{
"status": "affected",
"version": "17.7.1a"
},
{
"status": "affected",
"version": "16.12.6"
},
{
"status": "affected",
"version": "Fuji-16.9.8"
},
{
"status": "affected",
"version": "17.6.2"
},
{
"status": "affected",
"version": "17.8.1a"
},
{
"status": "affected",
"version": "16.12.7"
},
{
"status": "affected",
"version": "17.3.5"
},
{
"status": "affected",
"version": "17.6.3"
},
{
"status": "affected",
"version": "17.6.3a"
},
{
"status": "affected",
"version": "17.7.2"
},
{
"status": "affected",
"version": "17.9.1a"
},
{
"status": "affected",
"version": "17.6.4"
},
{
"status": "affected",
"version": "17.10.1a"
},
{
"status": "affected",
"version": "17.3.6"
},
{
"status": "affected",
"version": "16.12.8"
},
{
"status": "affected",
"version": "17.3.7"
},
{
"status": "affected",
"version": "17.9.2a"
},
{
"status": "affected",
"version": "17.6.5"
},
{
"status": "affected",
"version": "17.11.1a"
},
{
"status": "affected",
"version": "17.9.3a"
},
{
"status": "affected",
"version": "17.12.1a"
},
{
"status": "affected",
"version": "17.9.4"
},
{
"status": "affected",
"version": "17.6.6"
},
{
"status": "affected",
"version": "17.3.8"
},
{
"status": "affected",
"version": "17.3.8a"
},
{
"status": "affected",
"version": "17.6.6a"
},
{
"status": "affected",
"version": "17.9.4a"
},
{
"status": "affected",
"version": "17.12.2"
},
{
"status": "affected",
"version": "17.13.1a"
},
{
"status": "affected",
"version": "17.9.5a"
},
{
"status": "affected",
"version": "17.12.3"
},
{
"status": "affected",
"version": "17.6.7"
},
{
"status": "affected",
"version": "17.14.1a"
},
{
"status": "affected",
"version": "17.12.4"
},
{
"status": "affected",
"version": "17.12.3a"
},
{
"status": "affected",
"version": "17.15.1a"
},
{
"status": "affected",
"version": "17.6.8"
},
{
"status": "affected",
"version": "17.9.6"
},
{
"status": "affected",
"version": "17.6.8a"
},
{
"status": "affected",
"version": "17.16.1a"
},
{
"status": "affected",
"version": "17.9.5e"
},
{
"status": "affected",
"version": "17.12.4a"
},
{
"status": "affected",
"version": "17.15.2c"
},
{
"status": "affected",
"version": "17.9.5f"
},
{
"status": "affected",
"version": "17.12.4b"
},
{
"status": "affected",
"version": "17.15.2a"
},
{
"status": "affected",
"version": "17.12.5"
},
{
"status": "affected",
"version": "17.17.1"
},
{
"status": "affected",
"version": "17.12.5a"
},
{
"status": "affected",
"version": "17.9.7a"
},
{
"status": "affected",
"version": "17.15.3a"
},
{
"status": "affected",
"version": "17.15.3"
},
{
"status": "affected",
"version": "17.12.5b"
},
{
"status": "affected",
"version": "17.12.5c"
},
{
"status": "affected",
"version": "17.15.4"
},
{
"status": "affected",
"version": "17.9.7b"
},
{
"status": "affected",
"version": "17.18.1"
},
{
"status": "affected",
"version": "17.18.1a"
},
{
"status": "affected",
"version": "17.12.6"
},
{
"status": "affected",
"version": "17.9.8"
},
{
"status": "affected",
"version": "17.15.4c"
},
{
"status": "affected",
"version": "17.12.5d"
},
{
"status": "affected",
"version": "17.18.2"
},
{
"status": "affected",
"version": "26.1.1"
},
{
"status": "affected",
"version": "17.15.5"
},
{
"status": "affected",
"version": "17.15.5a"
},
{
"status": "affected",
"version": "17.12.7"
},
{
"status": "affected",
"version": "17.12.7a"
},
{
"status": "affected",
"version": "17.12.7b"
},
{
"status": "affected",
"version": "17.9.9"
},
{
"status": "affected",
"version": "17.18.3a"
},
{
"status": "affected",
"version": "17.12.8"
},
{
"status": "affected",
"version": "17.15.6"
},
{
"status": "affected",
"version": "17.18.4"
},
{
"status": "affected",
"version": "26.1.2"
},
{
"status": "affected",
"version": "17.9.10"
}
]
}
],
"source": "psirt@cisco.com"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "Multiple Cisco products are affected by a vulnerability in the generic routing encapsulation (GRE) tunnel decapsulation feature of the Snort 3 Detection Engine that could allow an unauthenticated, remote attacker to cause an unexpected restart of the Snort 3 Detection Engine.\r\n\r\nThis vulnerability is due to improper handling of nested GRE traffic. An attacker could exploit this vulnerability by sending a crafted GRE payload through an affected device. A successful exploit could allow the attacker to trigger an unexpected reload of the Snort 3 Detection Engine, resulting in either a bypass or denial of service (DoS) condition, depending on device configuration. For more information, see the section of this advisory. The Snort 3 Detection Engine will restart automatically. No manual intervention is required."
}
],
"id": "CVE-2026-20221",
"lastModified": "2026-10-22T14:17:40.940",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "LOW",
"baseScore": 5.8,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "CHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L",
"version": "3.1"
},
"exploitabilityScore": 3.9,
"impactScore": 1.4,
"source": "psirt@cisco.com",
"type": "Secondary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-20221",
"options": [
{
"exploitation": "none"
},
{
"automatable": "yes"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-10-22T13:23:54.810399Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-10-21T17:18:27.947",
"references": [
{
"source": "psirt@cisco.com",
"url": "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snort3-gre-JNpMHrTv"
}
],
"sourceIdentifier": "psirt@cisco.com",
"vulnStatus": "Awaiting Analysis",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-476"
}
],
"source": "psirt@cisco.com",
"type": "Secondary"
}
]
}
}
}
}
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Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.
Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline
Sightings and recorded dates, grouped by day · UTC
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.