CVE-2026-20019
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Denial of Service in Cisco Snort 3 NetFlow Detection Engine

Vulnerability report for CVE-2026-20019, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-10-21

Last updated on: 2026-10-22

Assigner: Cisco Systems, Inc.

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 Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published
2026-10-21
Last Modified
2026-10-22
Generated
2026-11-10
AI Q&A
2026-10-22
EPSS Evaluated
2026-11-09
NVD
EUVD

Affected Vendors & Products

Showing 203 associated CPEs
Vendor Product Version / Range
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.0.6
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.2.5
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.2.4.1
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.3.1.1
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.4.0
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.0.6.1
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.2.5.1
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.4.1
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.2.6
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.0.6.2
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.4.1.1
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.2.7
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.2.5.2
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.3.1.2
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.2.8
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.6.0
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.4.2
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.2.8.1
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.0.6.3
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.4.2.1
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.2.9
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.0.7
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.7.0
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.4.2.2
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.2.10
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.6.1
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.4.2.3
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.0.8
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.6.2
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.7.10
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.7.11
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.0.8.1
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.6.2.1
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.7.10.1
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.4.2.4
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.2.10.2
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.4.3
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.6.4
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 10.0.0
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.4.4
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.0.9
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.2.11
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.4.7
Cisco Cisco UTD SNORT IPS Engine Software 17.12.1a
Cisco Cisco UTD SNORT IPS Engine Software 17.12.2
Cisco Cisco UTD SNORT IPS Engine Software 17.13.1a
Cisco Cisco UTD SNORT IPS Engine Software 17.12.3
Cisco Cisco UTD SNORT IPS Engine Software 17.14.1a
Cisco Cisco UTD SNORT IPS Engine Software 17.12.4
Cisco Cisco UTD SNORT IPS Engine Software 17.12.3a
Cisco Cisco UTD SNORT IPS Engine Software 17.15.1a
Cisco Cisco UTD SNORT IPS Engine Software 17.16.1a
Cisco Cisco UTD SNORT IPS Engine Software 17.12.4a
Cisco Cisco UTD SNORT IPS Engine Software 17.15.2c
Cisco Cisco UTD SNORT IPS Engine Software 17.12.4b
Cisco Cisco UTD SNORT IPS Engine Software 17.15.2a
Cisco Cisco UTD SNORT IPS Engine Software 17.12.5
Cisco Cisco UTD SNORT IPS Engine Software 17.17.1
Cisco Cisco UTD SNORT IPS Engine Software 17.12.5a
Cisco Cisco UTD SNORT IPS Engine Software 17.15.3a
Cisco Cisco UTD SNORT IPS Engine Software 17.15.3
Cisco Cisco UTD SNORT IPS Engine Software 17.12.5b
Cisco Cisco UTD SNORT IPS Engine Software 17.12.5c
Cisco Cisco UTD SNORT IPS Engine Software 17.15.4
Cisco Cisco UTD SNORT IPS Engine Software 17.18.1
Cisco Cisco UTD SNORT IPS Engine Software 17.18.1a
Cisco Cisco UTD SNORT IPS Engine Software 17.12.6
Cisco Cisco UTD SNORT IPS Engine Software 17.15.4c
Cisco Cisco UTD SNORT IPS Engine Software 17.12.5d
Cisco Cisco UTD SNORT IPS Engine Software 17.18.2
Cisco Cisco UTD SNORT IPS Engine Software 26.1.1
Cisco Cisco UTD SNORT IPS Engine Software 17.15.5
Cisco Cisco UTD SNORT IPS Engine Software 17.15.5a
Cisco Cisco UTD SNORT IPS Engine Software 17.12.7
Cisco Cisco UTD SNORT IPS Engine Software 17.12.7a
Cisco Cisco UTD SNORT IPS Engine Software 17.12.7b
Cisco Cisco UTD SNORT IPS Engine Software 17.18.3a
Cisco Cisco UTD SNORT IPS Engine Software 17.12.8
Cisco Cisco UTD SNORT IPS Engine Software 17.15.6
Cisco Cisco UTD SNORT IPS Engine Software 17.18.4
Cisco Cisco UTD SNORT IPS Engine Software 26.1.2
Cisco Cisco Open Source Snort3 3.12.2.0
Cisco Cisco Open Source Snort3 3.1.2.0
Cisco Cisco Open Source Snort3 3.1.3.0
Cisco Cisco Open Source Snort3 3.1.4.0
Cisco Cisco Open Source Snort3 3.1.5.0
Cisco Cisco Open Source Snort3 3.1.6.0
Cisco Cisco Open Source Snort3 3.1.7.0
Cisco Cisco Open Source Snort3 3.1.8.0
Cisco Cisco Open Source Snort3 3.1.9.0
Cisco Cisco Open Source Snort3 3.1.10.0
Cisco Cisco Open Source Snort3 3.1.12.0
Cisco Cisco Open Source Snort3 3.1.13.0
Cisco Cisco Open Source Snort3 3.1.14.0
Cisco Cisco Open Source Snort3 3.1.15.0
Cisco Cisco Open Source Snort3 3.1.16.0
Cisco Cisco Open Source Snort3 3.1.17.0
Cisco Cisco Open Source Snort3 3.1.18.0
Cisco Cisco Open Source Snort3 3.1.19.0
Cisco Cisco Open Source Snort3 3.1.20.0
Cisco Cisco Open Source Snort3 3.1.21.0
Cisco Cisco Open Source Snort3 3.1.22.0
Cisco Cisco Open Source Snort3 3.1.23.0
Cisco Cisco Open Source Snort3 3.1.24.0
Cisco Cisco Open Source Snort3 3.1.25.0
Cisco Cisco Open Source Snort3 3.1.27.0
Cisco Cisco Open Source Snort3 3.1.28.0
Cisco Cisco Open Source Snort3 3.1.29.0
Cisco Cisco Open Source Snort3 3.1.30.0
Cisco Cisco Open Source Snort3 3.1.31.0
Cisco Cisco Open Source Snort3 3.1.32.0
Cisco Cisco Open Source Snort3 3.1.36.0
Cisco Cisco Open Source Snort3 3.1.38.0
Cisco Cisco Open Source Snort3 3.1.39.0
Cisco Cisco Open Source Snort3 3.1.40.0
Cisco Cisco Open Source Snort3 3.1.41.0
Cisco Cisco Open Source Snort3 3.1.42.0
Cisco Cisco Open Source Snort3 3.1.43.0
Cisco Cisco Open Source Snort3 3.1.45.0
Cisco Cisco Open Source Snort3 3.1.47.0
Cisco Cisco Open Source Snort3 3.1.48.0
Cisco Cisco Open Source Snort3 3.1.50.0
Cisco Cisco Open Source Snort3 3.1.51.0
Cisco Cisco Open Source Snort3 3.1.52.0
Cisco Cisco Open Source Snort3 3.1.53.0
Cisco Cisco Open Source Snort3 3.1.55.0
Cisco Cisco Open Source Snort3 3.1.56.0
Cisco Cisco Open Source Snort3 3.1.57.0
Cisco Cisco Open Source Snort3 3.1.58.0
Cisco Cisco Open Source Snort3 3.1.59.0
Cisco Cisco Open Source Snort3 3.1.60.0
Cisco Cisco Open Source Snort3 3.1.61.0
Cisco Cisco Open Source Snort3 3.1.62.0
Cisco Cisco Open Source Snort3 3.1.63.0
Cisco Cisco Open Source Snort3 3.1.64.0
Cisco Cisco Open Source Snort3 3.1.65.0
Cisco Cisco Open Source Snort3 3.1.66.0
Cisco Cisco Open Source Snort3 3.1.67.0
Cisco Cisco Open Source Snort3 3.1.69.0
Cisco Cisco Open Source Snort3 3.1.70.0
Cisco Cisco Open Source Snort3 3.1.71.0
Cisco Cisco Open Source Snort3 3.1.72.0
Cisco Cisco Open Source Snort3 3.1.73.0
Cisco Cisco Open Source Snort3 3.1.74.0
Cisco Cisco Open Source Snort3 3.1.75.0
Cisco Cisco Open Source Snort3 3.1.76.0
Cisco Cisco Open Source Snort3 3.1.77.0
Cisco Cisco Open Source Snort3 3.1.78.0
Cisco Cisco Open Source Snort3 3.1.81.0
Cisco Cisco Open Source Snort3 3.1.82.0
Cisco Cisco Open Source Snort3 3.1.83.0
Cisco Cisco Open Source Snort3 3.1.84.0
Cisco Cisco Open Source Snort3 3.2.1.0
Cisco Cisco Open Source Snort3 3.2.2.0
Cisco Cisco Open Source Snort3 3.3.0.0
Cisco Cisco Open Source Snort3 3.3.1.0
Cisco Cisco Open Source Snort3 3.3.2.0
Cisco Cisco Open Source Snort3 3.3.3.0
Cisco Cisco Open Source Snort3 3.3.4.0
Cisco Cisco Open Source Snort3 3.3.5.0
Cisco Cisco Open Source Snort3 3.3.7.0
Cisco Cisco Open Source Snort3 3.5.0.0
Cisco Cisco Open Source Snort3 3.5.1.0
Cisco Cisco Open Source Snort3 3.8.1.0
Cisco Cisco Open Source Snort3 3.6.0.0
Cisco Cisco Open Source Snort3 3.6.2.0
Cisco Cisco Open Source Snort3 3.9.3.0
Cisco Cisco Open Source Snort3 3.7.2.0
Cisco Cisco Open Source Snort3 3.7.0.0
Cisco Cisco Open Source Snort3 3.9.6.0
Cisco Cisco Open Source Snort3 3.10.0.0
Cisco Cisco Open Source Snort3 3.10.2.0
Cisco Cisco Open Source Snort3 3.7.4.0
Cisco Cisco Open Source Snort3 3.9.0.0
Cisco Cisco Open Source Snort3 3.5.2.0
Cisco Cisco Open Source Snort3 3.12.1.0
Cisco Cisco Open Source Snort3 3.6.1.0
Cisco Cisco Open Source Snort3 3.9.2.0
Cisco Cisco Open Source Snort3 3.6.3.0
Cisco Cisco Open Source Snort3 3.9.5.0
Cisco Cisco Open Source Snort3 3.7.1.0
Cisco Cisco Open Source Snort3 3.9.7.0
Cisco Cisco Open Source Snort3 3.7.3.0
Cisco Cisco Open Source Snort3 3.10.1.0
Cisco Cisco Open Source Snort3 3.9.1.0
Cisco Cisco Open Source Snort3 3.11.1.0
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.0.0
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.0.0.1
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.0.1
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.0.1.1
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.0.2
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.2.0
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.0.2.1
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.0.3
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.2.0.1
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.0.4
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.2.1
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.0.5
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.3.0
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.2.2
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.2.3
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.3.1
Cisco Cisco Secure Firewall Threat Defense (FTD) Software 7.2.4

Helpful Resources

Exploitability

CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-835 The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.

Attack-Flow Graph

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Executive Summary

This vulnerability affects Cisco products using the Snort 3 NetFlow Detection Engine. It allows an unauthenticated remote attacker to cause the Snort 3 Detection Engine to restart by sending a crafted UDP NetFlow Protocol packet. This results in a denial of service as packet inspection is interrupted.

Impact Analysis

If exploited, this vulnerability could disrupt network traffic inspection, leading to potential loss of security monitoring and increased risk of undetected malicious activity. It may cause temporary service interruptions for affected Cisco products.

Mitigation Strategies

Apply the latest security patches or updates provided by Cisco for affected Snort 3 and Cisco Secure Firewall Threat Defense (FTD) Software products to address the incomplete error checking in the NetFlow Detection Engine.

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