NULL pointer dereference in Cisco Cyber Vision
CVE-2026-20221
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.8 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
- Cisco Cyber Vision — versions 3.0.0, 3.0.1, 3.0.2
- Cisco Secure Firewall Threat Defense (Ftd) Software — versions 10.0.0, 7.0.0, 7.0.0.1
- Cisco Umbrella Insights Virtual Appliance — versions 1.5.4, 1.5.5, 1.5.6
- Cisco Utd Snort Ips Engine Software — versions 16.12.1a, 16.12.2, 16.12.3
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-20221?
- CVE-2026-20221 is a medium-severity vulnerability in Cisco Cyber Vision, classified under NULL Pointer Dereference. CVSS score: 5.8/10. Published 2026-10-21.
- How severe is CVE-2026-20221?
- Medium severity. CVSS v3 base score is 5.8 out of 10.