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CVE-2026-20043VulnerabilityPublished Updated

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

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Authoritative record:CVE-2026-20043· Critical 9.0

Not known to be exploited · CVSS 9.0 Critical.

Data as of 7 Nov 2026, 19:35 UTC

CVSS 3.1 base score
9.0Critical
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (cisco)CVSS 3.19.0
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 21 Oct 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 7 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
CiscoCisco Cyber VisionAffected
  • >=4.2.0 <4.3.0 – 5.8.1
65 affected builds
Fixed in–
CiscoCisco Open Source Snort3Affected
  • 3.1.2.0 – 3.12.2.0
105 affected builds
Fixed in–
CiscoCisco Secure Firewall Threat Defense (FTD) SoftwareAffected
  • 7.0.0 – 10.0.0
59 affected builds
Fixed in–
CiscoCisco UTD SNORT IPS Engine SoftwareAffected
  • 17.3.1a – 26.1.2
83 affected builds
Fixed in–

AI-suggested

Cisco has conducted an internal security review and released software hardening updates to address these vulnerabilities. However, no explicit patch or fixed version information is provided in the available data. Users should consult Cisco's official advisories and update to the latest hardened releases once available.

Description

CVE-2026-20043 is a critical vulnerability in Cisco-owned Open Source Snort 3 involving out-of-bounds write issues (CWE-787). Cisco's internal security review identified these flaws, leading to software hardening releases. The vulnerability has a high CVSS score of 9.0, indicating severe impact on confidentiality, integrity, and availability. No specific affected versions or patch links are provided in the data. There is no indication of known exploits in the wild.

References

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