Medium severity · published Oct 21, 2026
CVE-2026-20019
Multiple Cisco Products Snort 3 Netflow Denial of Service Vulnerabilities
New
5.8
CVSS
0.5%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
Low
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 44% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CO
Cisco Open Source Snort3 · Cisco
3.12.2.0; 3.1.2.0; 3.1.3.0; 3.1.4.0; 3.1.5.0; 3.1.6.0; +34 more · source: vendor
CS
Cisco Secure Firewall Threat Defense (FTD) Software · Cisco
7.0.0; 7.0.0.1; 7.0.1; 7.0.1.1; 7.0.2; 7.2.0; +34 more · source: vendor
CU
Cisco UTD SNORT IPS Engine Software · Cisco
17.12.1a; 17.12.2; 17.13.1a; 17.12.3; 17.14.1a; 17.12.4; +32 more · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-20019
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-20019
sec.cloudapps.cisco.com
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snort3-misc-dos-6mB22qAK
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