Remote Code Execution Vulnerability in Cisco Snort 3 Detection Engine
CVE-2026-20221

5.8MEDIUM

Key Information:

Vendor

Cisco
Status
Cisco Cyber Vision
Cisco Open Source Snort3
Cisco Secure Firewall Threat Defense (ftd) Software
Cisco Umbrella Insights Virtual Appliance
Vendor
CVE Published:
21 October 2026

Badges

👾 Exploit Exists

What is CVE-2026-20221?

A vulnerability exists in Cisco's Snort 3 Detection Engine, specifically related to the handling of generic routing encapsulation (GRE) tunnel decapsulation. This weakness could be exploited by an unauthenticated remote attacker who sends a specially crafted GRE payload to an affected device. If successful, the exploit may trigger an unexpected reload of the Snort 3 Detection Engine, potentially leading to a denial of service (DoS) condition or even allowing the attacker to bypass certain security measures, depending on the configuration of the affected device.

Affected Version(s)

Cisco Cyber Vision 3.0.0

Cisco Cyber Vision 3.0.2

Cisco Cyber Vision 3.0.3

References

https://sec.cloudapps.cisco.com/security/center/content/C...

CVSS V3.1

Score:
5.8
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Changed

Timeline

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

.