CVE-2026-20218
Multiple Cisco Products Snort 3 Visual Basic for Applications Buffer Overflow Denial of Service Vulnerability
CVE-2026-20218: Multiple Cisco Products Snort 3 Visual Basic for Applications Buffer Overflow Denial of Service Vulnerability. Not in the CISA KEV catalog.
Compare the source-linked records below. Ratings and product/version details belong to each advisory; they are not a single CVE-wide score or proof that every listed product is affected. How VulniPulse collects and checks evidence.
CVE-2026-20218 at a glance
- CISA KEV
- Not listed (catalog checked )
- Highest advisory severity
- Medium
- CVSS base score
- 5.8 (Cisco)
- Fixed releases
- Cisco: 3.12.4.0, 17.12.8, 17.15.6, 17.18.5, 26.1.2, 26.2.1
- Vendor advisories
- 2 from Cisco
- VulniPulse record
- Published · Updated
Scores, vectors, weaknesses and fixed releases are quoted from vendor advisories that cover only CVE-2026-20218; bulletin-wide values are not repeated here.
Is CVE-2026-20218 exploited?
No exploitation is reported in the sources VulniPulse tracks: CVE-2026-20218 is not in the CISA KEV catalog (checked ) and no tracked advisory for it reports exploitation. That is not proof the vulnerability cannot be exploited.
How do I fix CVE-2026-20218?
Upgrade to a fixed release named by the vendor:
- Cisco: 3.12.4.0, 17.12.8, 17.15.6, 17.18.5, 26.1.2, 26.2.1
- Upgrade to the first fixed release for your train per the Fixed Releases table in this advisory. (Cisco)
- Release 3.x: upgrade to 3.12.4.0. (Cisco)
Vendor advisory comparison
Cisco
2 advisories- Advisory severityMedium5.8
Medium [CVE-2026-20218] Multiple Cisco Products Snort 3 Visual Basic for Applications Buffer Overflow Denial of Service Vulnerability
cisco-sa-snort3-vba-bufdos-jAuFdvn9Source published Source 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 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. Cisco has released software updates that address this vulnerability. There is a workaround that addresses this vulnerability. This advisory is part of a group…
- Affected products in this advisory
- Secure Firewall Threat Defense (FTD) Software
- Firepower 2100 Series
- Firepower 1000 Series
- 3000 Series Industrial Security Appliances (ISA)
4 more entries in the full advisory.
- Source-reported affected versions
- Scope: For information about which products were affected by this vulnerability at the time of publication, see the following sections. Open Source Snort 3
- Release 3.x (first fixed: 3.12.4.0)
- Release 17.12 (first fixed: 17.12.8)
- Release 17.15 (first fixed: 17.15.6)
3 more entries in the full advisory.
- Source-reported fixed versions
- 3.12.4.0
- 17.12.8
- 17.15.6
- 17.18.5
2 more entries in the full advisory.
- Mitigation guidance
- Upgrade to the first fixed release for your train per the Fixed Releases table in this advisory.
- Release 3.x: upgrade to 3.12.4.0.
- Release 17.12: upgrade to 17.12.8.
- Release 17.15: upgrade to 17.15.6.
3 more entries in the full advisory.
- Workarounds
- There is a workaround that addresses this vulnerability.
- This vulnerability is due to VBA decompression, which is not enabled by default for any Snort 3 Inspector. If VBA decompression is disabled until the device can be upgraded to a fixed software release, the device will not be affected by this vulnerability. For more details on how to remove the VBA configuration, see the following references:
- Firewall Management Center Features in Version 7.2.0
- Snort 3 Inspector Reference
2 more entries in the full advisory.
- Advisory severityUnrated
Advisory [CVE-2026-20011 +12] Cisco Advance Notification for Publication of October 21, 2026, Security Advisories
cisco-sa-notice-QGwHnJ6kSource published Source updated
This bulletin covers 13 CVEs. The products, versions, score and guidance below describe the bulletin; check its source for applicability to this specific CVE.
On October 21, 2026, the Cisco Product Security Incident Response Team (PSIRT) published the following advisories. To remediate the vulnerabilities that were disclosed on October 21, 2026, Cisco strongly recommends that customers upgrade to the fixed software that is indicated in the advisories. For more information about changes in Cisco PSIRT vulnerability disclosure, see Strengthening the Foundation: A Predictable, Customer-Focused Response to AI-Accelerated Vulnerability Discovery. Snort 3 Cisco Security Advisory CVE ID Security Impact Rating CVSS Base Score Critical 9.0 High 7.8 Medium 5.8 5.3 Cisco Expressway and Unified Communications Products
- Affected products in this advisory
- No product details extracted. Check the source bulletin.
- Source-reported affected versions
- Affected-version details not available in this record.
- Source-reported fixed versions
- No fixed-version detail extracted. This does not mean no fix exists.
- Mitigation guidance
- To remediate the vulnerabilities that were disclosed on October 21, 2026, Cisco strongly recommends that customers upgrade to the fixed software that is indicated in the advisories.
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