Critical severity · published Oct 21, 2026
CVE-2026-20043
Multiple Cisco Products Snort 3 Software Hardening Release: October 2026
New
9.0
CVSS
0.4%
EPSS
No
On KEV
Description
As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco owned Open Source Snort 3 Software engineering team has conducted a comprehensive internal security review. This review resulted in software hardening releases that address multiple internally discovered vulnerabilities.
The vulnerabilities tracked by CVE-2026-20043 are related to issues concerning out-of-bounds writes that are grouped under the Common Weakness Enumeration (CWE) Base CWE-787.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 30% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CC
Cisco Cyber Vision · Cisco
3.0.0; 3.0.2; 3.0.3; 3.0.1; 3.1.0; 3.0.4; +34 more · source: vendor
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; 7.0.2.1; +34 more · source: vendor
CU
Cisco UTD SNORT IPS Engine Software · Cisco
17.3.1a; 17.3.2; 17.4.1a; 17.5.1; 17.3.3; 17.5.1a; +34 more · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-20043
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-20043
sec.cloudapps.cisco.com
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-hardening-snort3-ybgmhTQe
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