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Vulnerabilities

Vulnerability · CVE-2026-20218

Multiple Cisco Products Snort 3 Visual Basic for Applications Buffer Overflow Denial of Service Vulnerability

Published Oct 21, 2026 · catalog updated Oct 22, 2026 · Cisco

Last checked Nov 6, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-20218. EPSS is 0.63%. Act only if a listed version of Cisco is installed.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High8.1
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.63%
Remediation
Advisory link
Affected products
Cisco

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.

No affected version ranges are stored yet. Use the vendor advisory before you decide this record does not apply.

How to fix CVE-2026-20218

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-20218. EPSS is 0.63%. Act only if a listed version of Cisco is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-121: Stack-based Buffer Overflow. EPSS 0.63%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Cisco security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 21, 2026 · NIST NVD

    Detected

    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 attack

  2. Oct 22, 2026 · NIST NVD

    Updated

    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 attack

Sources

  • Cisco Security AdvisoriesVendor advisoryCVE-2026-20218

    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

    sec.cloudapps.cisco.com
  • CVE.orgVulnerability recordCVE-2026-20218

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-20218

    30-day exploitation probability 0.63%

    first.org
  • NIST NVDVulnerability recordCVE-2026-20218

    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. T

    nvd.nist.gov
  • Zero Day InitiativeCoordinated disclosureZDI-26-788

    This vulnerability allows remote attackers to execute arbitrary code on affected installations of Cisco Snort. Authentication is not required to exploit this vulnerability. The ZDI has assigned a CVSS rating of 8.1. The following CVEs are assigned: CVE-2026-20218.

    zerodayinitiative.com

References

Freshness

Last verified in this catalog Nov 3, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • Cisco Security AdvisoriesNov 6, 2026
  • Zero Day InitiativeNov 4, 2026
  • FIRST EPSSNov 3, 2026
  • NIST NVDOct 22, 2026
  • CVE.orgOct 21, 2026