Advisories

Cisco Advance Notification for Publication of October 21, 2026, Security Advisories

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 Multiple Cisco Products Snort 3 Security Hardening Release: October 2026 CVE-2026-20043 CVE-2026-20236 CVE-2026-20291 CVE-2026-203

Read at Cisco PSIRT Security Advisories

Vendor

Cisco

EPSS

0.005 (p45)

• Cisco PSIRT Security Advisories (sec.cloudapps.cisco.com)
• CVE-2026-20043 on this site · NVD · CVE.org · Vulnpedia
• CVE-2026-20236 on this site · NVD · CVE.org · Vulnpedia
• CVE-2026-20291 on this site · NVD · CVE.org · Vulnpedia
• CVE-2026-20356 on this site · NVD · CVE.org · Vulnpedia
• CVE-2026-76524 on this site · NVD · CVE.org · Vulnpedia

Other items that share a CVE or were clustered with this one.

1. 30
   Cisco advisory Cisco PSIRT 9d ago

   Multiple Cisco Products Snort 3 SMTP MIME Denial of Service Vulnerability

   Fix available CVE-2026-20011 Cisco
2. 30
   Cisco advisory Cisco PSIRT 9d ago

   Multiple Cisco Products Snort 3 Security Hardening Release: October 2026

   Fix available CVE-2026-20043CVE-2026-20236CVE-2026-20291+1 more Cisco
3. 30
   Cisco advisory Cisco PSIRT 9d ago

   Multiple Cisco Products Snort 3 Denial of Service Vulnerabilities

   Fix available CVE-2026-20019CVE-2026-20179CVE-2026-20197+1 more Cisco
4. 30
   Cisco advisory Cisco PSIRT 9d ago

   Multiple Cisco Products Snort 3 Generic Routing Encapsulation Denial of Service Vulnerability

   Fix available CVE-2026-20221 Cisco
5. 30
   Cisco advisory Cisco PSIRT 9d ago

   Multiple Cisco Products Snort 3 Denial of Service Vulnerability

   Fix available CVE-2026-76445 Cisco
6. 36
   Cisco advisory Cisco PSIRT 9d ago

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

   Fix available CVE-2026-20218 Cisco
7. 33
   ZDI advisory ZDI 10d ago

   Cisco Snort OLE VBA Decompression Stack-based Buffer Overflow Remote Code Execution Vulnerability

   CVSS 8.1 CVE-2026-20218 Cisco
8. 27
   CVE NVD 10d ago

   A vulnerability in the control channel socket implementation of Open Source Snort 3 could allow an authenticated, local attacker with low…

   CVSS 7.8 CVE-2026-76524 Cisco
9. 20
   CVE NVD 10d ago

   Multiple Cisco products are affected by a vulnerability in the memory management implementation of Snort 3 that could allow an unauthenticated…

   CVSS 5.8 CVE-2026-76489 Cisco
10. 20
    CVE NVD 10d ago

    Multiple Cisco products are affected by a vulnerability in the Snort 3 Detection Engine that could allow an unauthenticated, remote attacker to cause…

    CVSS 5.3 CVE-2026-76445 Cisco
11. 27
    CVE NVD 10d ago

    As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco owned Open Source Snort 3 Software engineering team has…

    CVSS 7.5 CVE-2026-20356 Cisco
12. 27
    CVE NVD 10d ago

    As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco owned Open Source Snort 3 Software engineering team has…

    CVSS 7.8 CVE-2026-20291 Cisco
13. 27
    CVE NVD 10d ago

    As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco owned Open Source Snort 3 Software engineering team has…

    CVSS 7.5 CVE-2026-20236 Cisco
14. 20
    CVE NVD 10d ago

    Multiple Cisco products are affected by a vulnerability in the generic routing encapsulation (GRE) tunnel decapsulation feature of the Snort 3…

    CVSS 5.8 CVE-2026-20221 Cisco
15. 26
    CVE NVD 10d ago

    A vulnerability in the Snort 3 Visual Basic for Applications (VBA) Decompression Engine of multiple Cisco products could allow an unauthenticated…

    CVSS 5.8 CVE-2026-20218 Cisco
16. 20
    CVE NVD 10d ago

    Multiple Cisco products are affected by a vulnerability in the Snort 3 Teredo Detection Engine that could allow an unauthenticated, remote attacker…

    CVSS 5.8 CVE-2026-20197 Cisco
17. 20
    CVE NVD 10d ago

    Multiple Cisco products are affected by a vulnerability in the Snort 3 Generic Routing Encapsulation (GRE) Detection Engine that could allow an…

    CVSS 5.8 CVE-2026-20179 Cisco
18. 35
    CVE NVD 10d ago

    As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco owned Open Source Snort 3 Software engineering team has…

    CVSS 9.0 CVE-2026-20043 Cisco
19. 20
    CVE NVD 10d ago

    Multiple Cisco products are affected by a vulnerability in the Snort 3 NetFlow Detection Engine that could allow an unauthenticated, remote attacker…

    CVSS 5.8 CVE-2026-20019 Cisco
20. 20
    CVE NVD 10d ago

    Multiple Cisco products are affected by a vulnerability in the Snort 3 SMTP MIME Decoder that could allow an unauthenticated, remote attacker to…

    CVSS 5.8 CVE-2026-20011 Cisco