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CVE-2026-20221: NULL Pointer Dereference in Cisco Cisco Cyber Vision

0
Medium
VulnerabilityCVE-2026-20221cvecve-2026-20221
Published: 10/21/2026 (10/21/2026, 16:12:53 UTC)
Source: CVE Database V5
Vendor/Project: Cisco
Product: Cisco Cyber Vision

Description

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.

CVSS v3.1

Score 5.8medium

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
None
Integrity
None
Availability
Low
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L

Affected software

Cisco

Cisco Cyber Vision

Affected versions
=3.0.0=3.0.2=3.0.3=3.0.1=3.1.0=3.0.4=3.1.1=3.1.2=3.2.0=3.0.5=3.2.1=3.0.6=3.2.2=3.2.3=3.2.4=4.0.0=4.0.1=4.0.2=4.0.3=4.1.0=4.1.1=4.1.2=4.1.3=4.1.4=4.2.0=4.2.1=4.1.5=4.2.2=>=4.2.0 <4.3.0=4.2.3=4.2.4=4.2.6=4.1.6=4.3.0=4.3.1=4.3.2=4.3.3=4.4.0=4.4.1=4.4.2=4.4.3=4.1.7=5.0.0=5.0.1=5.0.2=5.1.0=5.1.1=5.1.2=5.1.3=5.2.0=5.2.1=5.3.0=5.3.1=5.3.2=5.3.3=5.5.1=5.6.1=5.6.0=5.4.0=5.4.1=5.4.2

Cisco

Cisco Open Source Snort3

Affected versions
=3.12.2.0=3.1.2.0=3.1.3.0=3.1.4.0=3.1.5.0=3.1.6.0=3.1.7.0=3.1.8.0=3.1.9.0=3.1.10.0=3.1.12.0=3.1.13.0=3.1.14.0=3.1.15.0=3.1.16.0=3.1.17.0=3.1.18.0=3.1.19.0=3.1.20.0=3.1.21.0=3.1.22.0=3.1.23.0=3.1.24.0=3.1.25.0=3.1.27.0=3.1.28.0=3.1.29.0=3.1.30.0=3.1.31.0=3.1.32.0=3.1.36.0=3.1.38.0=3.1.39.0=3.1.40.0=3.1.41.0=3.1.42.0=3.1.43.0=3.1.45.0=3.1.47.0=3.1.48.0=3.1.50.0=3.1.51.0=3.1.52.0=3.1.53.0=3.1.55.0=3.1.56.0=3.1.57.0=3.1.58.0=3.1.59.0=3.1.60.0=3.1.61.0=3.1.62.0=3.1.63.0=3.1.64.0=3.1.65.0=3.1.66.0=3.1.67.0=3.1.69.0=3.1.70.0=3.1.71.0=3.1.72.0=3.1.73.0=3.1.74.0=3.1.75.0=3.1.76.0=3.1.77.0=3.1.78.0=3.1.81.0=3.1.82.0=3.1.83.0=3.1.84.0=3.2.1.0=3.2.2.0=3.3.0.0=3.3.1.0=3.3.2.0=3.3.3.0=3.3.4.0=3.3.5.0=3.3.7.0=3.5.0.0=3.5.1.0=3.8.1.0=3.6.0.0=3.6.2.0=3.9.3.0=3.7.2.0=3.7.0.0=3.9.6.0=3.10.0.0=3.10.2.0=3.7.4.0=3.9.0.0=3.5.2.0=3.12.1.0=3.6.1.0=3.9.2.0=3.6.3.0=3.9.5.0=3.7.1.0=3.9.7.0=3.7.3.0=3.10.1.0=3.9.1.0=3.11.1.0

Cisco

Cisco Secure Firewall Threat Defense (FTD) Software

Affected versions
=7.0.0=7.0.0.1=7.0.1=7.0.1.1=7.0.2=7.2.0=7.0.2.1=7.0.3=7.2.0.1=7.0.4=7.2.1=7.0.5=7.3.0=7.2.2=7.2.3=7.3.1=7.2.4=7.0.6=7.2.5=7.2.4.1=7.3.1.1=7.4.0=7.0.6.1=7.2.5.1=7.4.1=7.2.6=7.0.6.2=7.4.1.1=7.2.7=7.2.5.2=7.3.1.2=7.2.8=7.6.0=7.4.2=7.2.8.1=7.0.6.3=7.4.2.1=7.2.9=7.0.7=7.7.0=7.4.2.2=7.2.10=7.6.1=7.4.2.3=7.0.8=7.6.2=7.7.10=7.7.11=7.0.8.1=7.6.2.1=7.7.10.1=7.4.2.4=7.2.10.2=7.4.3=7.6.4=10.0.0=7.4.4=7.0.9=7.2.11=7.4.7

Cisco

Cisco Umbrella Insights Virtual Appliance

Affected versions
=2.6.0=2.5.6=2.5=2.4.12=2.7=2.6.2=2.5.5=2.5.4=2.8=2.6.1=2.5.7=1.5.4=1.5.5=1.5.6=2.0.0=2.0.2=2.0.3=2.1.0=2.1.2=2.1.4=2.1.5=2.2=2.2.1=2.3=2.3.1=2.4=2.4.4=2.4.6=2.8.9=3.0=3.1=3.2=2.8.1=2.8.2=2.8.3=2.8.4=2.8.5=3.0.1=3.0.2=3.0.4=3.0.5=3.1.1=3.1.2=3.1.3=3.1.4=3.2.1=3.2.2=3.2.3=3.3=3.3.1=3.3.2=3.3.3=3.3.4=3.4=3.4.1=3.4.2=3.4.3=3.4.4=3.4.5=3.4.6=3.5=2.7.1=2.7.2=2.7.6=2.7.9=2.7.10=3.5.1=3.5.2=3.6.1=3.6.2=3.7=3.7.1=3.8.3

Cisco

Cisco UTD SNORT IPS Engine Software

Affected versions
=3.17.1S=16.12.3=16.12.4=17.3.1a=16.6.6=16.12.2=3.17.0S=16.6.5=17.2.1r=17.1.1=16.6.7a=16.6.1=16.12.1a=17.3.2=17.4.1a=16.12.5=17.5.1=16.6.9=17.3.3=17.5.1a=17.3.4=17.3.4a=17.4.2=17.4.1b=17.6.1a=16.6.10=17.7.1a=16.12.6=17.6.2=17.8.1a=16.12.7=17.3.5=17.6.3=17.6.3a=17.7.2=17.9.1a=17.6.4=17.10.1a=17.3.6=16.12.8=17.3.7=17.9.2a=17.6.5=17.11.1a=17.9.3a=17.12.1a=17.9.4=17.6.6=17.3.8=17.3.8a=17.6.6a=17.9.4a=17.12.2=17.13.1a=17.9.5a=17.12.3=17.6.7=17.14.1a=17.12.4=17.12.3a=17.15.1a=17.6.8=17.9.6=17.6.8a=17.16.1a=17.9.5e=17.12.4a=17.15.2c=17.9.5f=17.12.4b=17.15.2a=17.12.5=17.17.1=17.12.5a=17.9.7a=17.15.3a=17.15.3=17.12.5b=17.12.5c=17.15.4=17.9.7b=17.18.1=17.18.1a=17.12.6=17.9.8=17.15.4c=17.12.5d=17.18.2=26.1.1=17.15.5=17.15.5a=17.12.7=17.12.7a=17.12.7b=17.9.9=17.18.3a=17.12.8=17.15.6=17.18.4=26.1.2=17.9.10

Technical Details

Data Version
5.2
Assigner Short Name
cisco
Date Reserved
2025-10-08T11:59:15.398Z
Cvss Version
3.1
State
PUBLISHED

Threat ID: 6ad8e8d24d27ba8daac3b6ba

Added to database: 10/21/2026, 16:31:14 UTC

Last updated: 10/22/2026, 00:01:13 UTC

Views: 4

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