Vulnerability in Cisco Cyber Vision

[ Description ]Official 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.

[ Fixes ]Fixes and patches

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ Advisories ]Government CERT advisories

• NCSC-NL22 Oct 2026NCSC-2026-0450

  Vulnerabilities fixed in Snort 3 from Cisco Translated from Dutch

  Probability/damage M/HCVE-2026-20011CVE-2026-20019CVE-2026-20043+10 more CVEs
• BSI CERT-Bund21 Oct 2026WID-SEC-2026-4104

  Cisco products (IOS XE, SFTD) and Snort: Multiple vulnerabilities Translated from German

  Risk highCVE-2026-20236CVE-2026-20011CVE-2026-20356+10 more CVEs

[ References ]References

• sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snort3-g…