CVE-2026-20356
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DoS Vulnerability in Snort 3 Software

Publication date: 2026-10-21

Last updated on: 2026-11-07

Assigner: Cisco Systems, Inc.

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-2026-20356 are related to issues concerning uncontrolled resource consumption that are grouped under the Common Weakness Enumeration (CWE) Base CWE-400.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published
2026-10-21
Last Modified
2026-11-07
Generated
2026-11-10
AI Q&A
2026-10-22
EPSS Evaluated
2026-11-09
NVD
CVE-2026-20356
EUVD
EUVD-2026-107380

Affected Vendors & Products

Showing 268 associated CPEs
Vendor Product Version / Range
Cisco Cisco Cyber Vision 3.0.0
Cisco Cisco Cyber Vision 3.0.2
Cisco Cisco Cyber Vision 3.0.3
Cisco Cisco Cyber Vision 3.0.1
Cisco Cisco Cyber Vision 3.1.0
Cisco Cisco Cyber Vision 3.0.4
Cisco Cisco Cyber Vision 3.1.1
Cisco Cisco Cyber Vision 3.1.2
Cisco Cisco Cyber Vision 3.2.0
Cisco Cisco Cyber Vision 3.0.5
Cisco Cisco Cyber Vision 3.2.1
Cisco Cisco Cyber Vision 3.0.6
Cisco Cisco Cyber Vision 3.2.2
Cisco Cisco Cyber Vision 3.2.3
Cisco Cisco Cyber Vision 3.2.4
Cisco Cisco Cyber Vision 4.0.0
Cisco Cisco Cyber Vision 4.0.1
Cisco Cisco Cyber Vision 4.0.2
Cisco Cisco Cyber Vision 4.0.3
Cisco Cisco Cyber Vision 4.1.0
Cisco Cisco Cyber Vision 4.1.1
Cisco Cisco Cyber Vision 4.1.2
Cisco Cisco Cyber Vision 4.1.3
Cisco Cisco Cyber Vision 4.1.4
Cisco Cisco Cyber Vision 4.2.0
Cisco Cisco Cyber Vision 4.2.1
Cisco Cisco Cyber Vision 4.1.5
Cisco Cisco Cyber Vision 4.2.2
Cisco Cisco Cyber Vision 4.2.X
Cisco Cisco Cyber Vision 4.2.3
Cisco Cisco Cyber Vision 4.2.4
Cisco Cisco Cyber Vision 4.2.6
Cisco Cisco Cyber Vision 4.1.6
Cisco Cisco Cyber Vision 4.3.0
Cisco Cisco Cyber Vision 4.3.1
Cisco Cisco Cyber Vision 4.3.2
Cisco Cisco Cyber Vision 4.3.3
Cisco Cisco Cyber Vision 4.4.0
Cisco Cisco Cyber Vision 4.4.1
Cisco Cisco Cyber Vision 4.4.2
Cisco Cisco Cyber Vision 4.4.3
Cisco Cisco Cyber Vision 4.1.7
Cisco Cisco Cyber Vision 5.0.0
Cisco Cisco Cyber Vision 5.0.1
Cisco Cisco Cyber Vision 5.0.2
Cisco Cisco Cyber Vision 5.1.0
Cisco Cisco Cyber Vision 5.1.1
Cisco Cisco Cyber Vision 5.1.2
Cisco Cisco Cyber Vision 5.1.3
Cisco Cisco Cyber Vision 5.2.0
Cisco Cisco Cyber Vision 5.2.1
Cisco Cisco Cyber Vision 5.3.0
Cisco Cisco Cyber Vision 5.3.1
Cisco Cisco Cyber Vision 5.3.2
Cisco Cisco Cyber Vision 5.3.3
Cisco Cisco Cyber Vision 5.5.1
Cisco Cisco Cyber Vision 5.6.1
Cisco Cisco Cyber Vision 5.4.0
Cisco Cisco Cyber Vision 5.4.1
Cisco Cisco Cyber Vision 5.4.2
Cisco Cisco Cyber Vision 5.7.0
Cisco Cisco Cyber Vision 5.8.1
Cisco Cisco Cyber Vision 5.7.1
Cisco Cisco Cyber Vision 5.8.0
Cisco Cisco Cyber Vision 5.5.2
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
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

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-400 The product does not properly control the allocation and maintenance of a limited resource.

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Executive Summary

CVE-2026-20356 is a vulnerability in Cisco's Open Source Snort 3 software and related products. It involves uncontrolled resource consumption, which can lead to system slowdowns or crashes. The issue is categorized under CWE-400, indicating a weakness where software does not properly control resource usage.

Impact Analysis

This vulnerability can cause denial-of-service conditions by consuming excessive system resources. Affected systems may become unresponsive or crash, disrupting network operations and security monitoring. Users of Cisco Cyber Vision, Secure Firewall Threat Defense, UTD SNORT IPS Engine, and Open Source Snort3 are potentially impacted.

Mitigation Strategies

Apply the latest security patches or updates from Cisco for affected products like Snort3, Cyber Vision, or Secure Firewall Threat Defense.

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