Multiple Cisco Products Snort 3 Denial of Service Vulnerabilities

Multiple Cisco products are affected by vulnerabilities in the Snort 3 Detection Engine that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart unexpectedly, resulting in a denial of service (DoS) condition.

For more information about these vulnerabilities, see the Details ["#details"] section of this advisory.

Cisco has released software updates that address these vulnerabilities. There are no workarounds that address these vulnerabilities.

This advisory is part of a group of advisories. For a complete list of the advisories and links to them, see Cisco Advance Notification for Publication of October 21, 2026, Security Advisories ["https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-notice-QGwHnJ6k"]. In addition, for further documentation of improvements and fixes in Open Source Snort 3, see Multiple Cisco Products Snort 3 Security Hardening Release: October 2026 ["https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-hardening-snort3-ybgmhTQe"].

CVE-2026-76489 — Multiple Cisco Products Snort 3 Generic File Processing Memory Exhaustion Denial of Service Vulnerability (CVSS 3.1 5.8, CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L) CVE-2026-20019 — Multiple Cisco Products Snort 3 Netflow Denial of Service Vulnerabilities (CVSS 3.1 5.8, CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L) CVE-2026-20179 — Multiple Cisco Products Snort 3 Generic Routing Encapsulation Denial of Service Vulnerabilities (CVSS 3.1 5.8, CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L) CVE-2026-20197 — Multiple Cisco Products Snort 3 Teredo Protocol Denial of Service Vulnerability (CVSS 3.1 5.8, CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L)