CVE-2026-20218

MEDIUM 5.8

Cisco Secure Firewall Threat Defense Snort 3 Visual Basic for Applications Buffer Overflow Denial of Service Vulnerability

CVSS Score

5.8

EPSS Score

0.0%

EPSS Percentile

0th

A vulnerability in the Snort 3 Visual Basic for Applications (VBA) Decompression Engine of multiple Cisco products could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to restart unexpectedly, resulting in a denial of service (DoS) condition. This vulnerability is due to improper range checking when Snort 3 decompresses VBA data, which is user controlled. An attacker could exploit this vulnerability by sending crafted VBA data to the Snort 3 Detection Engine of a targeted device. A successful exploit could allow the attacker to cause an overflow of stack data, which could result in a DoS condition.

CWE	CWE-121
Vendor	cisco
Product	cisco open source snort3
Ecosystems	Networking
Industries	NetworkingTelecommunications
Published	Oct 21, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Changed

Confidentiality

None

Integrity

None

Availability

Low

Affected Versions

Cisco / Cisco Open Source Snort3

3.12.2.0 3.1.2.0 3.1.3.0 3.1.4.0 3.1.5.0 3.1.6.0 3.1.7.0 3.1.8.0 3.1.9.0 3.1.10.0 3.1.12.0 3.1.13.0 3.1.14.0 3.1.15.0 3.1.16.0 3.1.17.0 3.1.18.0 3.1.19.0 3.1.20.0 3.1.21.0 3.1.22.0 3.1.23.0 3.1.24.0 3.1.25.0 3.1.27.0 3.1.28.0 3.1.29.0 3.1.30.0 3.1.31.0 3.1.32.0 3.1.36.0 3.1.38.0 3.1.39.0 3.1.40.0 3.1.41.0 3.1.42.0 3.1.43.0 3.1.45.0 3.1.47.0 3.1.48.0 3.1.50.0 3.1.51.0 3.1.52.0 3.1.53.0 3.1.55.0 3.1.56.0 3.1.57.0 3.1.58.0 3.1.59.0 3.1.60.0 3.1.61.0 3.1.62.0 3.1.63.0 3.1.64.0 3.1.65.0 3.1.66.0 3.1.67.0 3.1.69.0 3.1.70.0 3.1.71.0 3.1.72.0 3.1.73.0 3.1.74.0 3.1.75.0 3.1.76.0 3.1.77.0 3.1.78.0 3.1.81.0 3.1.82.0 3.1.83.0 3.1.84.0 3.2.1.0 3.2.2.0 3.3.0.0 3.3.1.0 3.3.2.0 3.3.3.0 3.3.4.0 3.3.5.0 3.3.7.0 3.5.0.0 3.5.1.0 3.8.1.0 3.6.0.0 3.6.2.0 3.9.3.0 3.7.2.0 3.7.0.0 3.9.6.0 3.10.0.0 3.10.2.0 3.7.4.0 3.9.0.0 3.5.2.0 3.12.1.0 3.6.1.0 3.9.2.0 3.6.3.0 3.9.5.0 3.7.1.0 3.9.7.0 3.7.3.0 3.10.1.0 3.9.1.0 3.11.1.0

Cisco / Cisco Secure Firewall Threat Defense (FTD) Software

7.2.0 7.2.0.1 7.2.1 7.3.0 7.2.2 7.2.3 7.3.1 7.2.4 7.2.5 7.2.4.1 7.3.1.1 7.4.0 7.2.5.1 7.4.1 7.2.6 7.4.1.1 7.2.7 7.2.5.2 7.3.1.2 7.2.8 7.6.0 7.4.2 7.2.8.1 7.4.2.1 7.2.9 7.7.0 7.4.2.2 7.2.10 7.6.1 7.4.2.3 7.6.2 7.7.10 7.7.11 7.6.2.1 7.7.10.1 7.4.2.4 7.2.10.2 7.4.3 7.6.4 10.0.0 7.4.4 7.2.11 7.4.7

Cisco / Cisco UTD SNORT IPS Engine Software

17.12.1a 17.12.2 17.13.1a 17.12.3 17.14.1a 17.12.4 17.12.3a 17.15.1a 17.16.1a 17.12.4a 17.15.2c 17.12.4b 17.15.2a 17.12.5 17.17.1 17.12.5a 17.15.3a 17.15.3 17.12.5b 17.12.5c 17.15.4 17.18.1 17.18.1a 17.12.6 17.15.4c 17.12.5d 17.18.2 26.1.1 17.15.5 17.15.5a 17.12.7 17.12.7a 17.12.7b 17.18.3a 17.12.8 17.15.6 17.18.4 26.1.2

References

NVD ↗ CVE.org ↗ EPSS Data ↗

sec.cloudapps.cisco.com: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snort3-vba-bufdos-jAuFdvn9