Vulnerability in Cisco Open Source Snort3

[ Description ]Official description

Multiple Cisco products are affected by a vulnerability in the Snort 3 NetFlow Detection Engine that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart, resulting in an interruption of packet inspection. This vulnerability is due to incomplete error checking when Snort 3 parses UDP Netflow Protocol packets. An attacker could exploit this vulnerability by sending a single crafted Netflow packet through an established connection to be parsed by Snort 3. A successful exploit could allow the attacker to cause the Snort 3 Detection Engine to restart unexpectedly, resulting in a DoS condition.

[ 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-m…