Secure Firewall Threat DefenseApplication · Cisco
CVE-2026-20007
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedA vulnerability in the Snort 2 and Snort 3 deep packet inspection of Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass configured Snort rules and allow traffic onto the network that should have been dropped. This vulnerability is due to a logic error in the integration of the Snort Engine rules with Cisco Secure FTD Software that could allow different Snort rules to be hit when deep inspection of the packet is performed for the inner and outer connections. An attacker could exploit this vulnerability by sending crafted traffic to a targeted device that would hit configured Snort rules. A successful exploit could allow the attacker to send traffic to a network where it should have been denied.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceA logic error in Cisco Secure FTD's integration with the Snort 2/3 inspection engine allows different Snort rules to be triggered during deep packet inspection of inner versus outer connections. This discrepancy enables crafted traffic to bypass configured Snort rules that should block it.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
Secure Firewall Threat DefenseApplication
= 6.4.0= 6.4.0.1= 6.4.0.2= 6.4.0.3= 6.4.0.4= 6.4.0.5= 6.4.0.6= 6.4.0.7= 6.4.0.8= 6.4.0.9= 6.4.0.10= 6.4.0.11CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Changed
- Confidentiality
- None
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify the Cisco FTD installationRun 'show version' or check the FTD device management interface to confirm the device is running Cisco Secure FTD (Firepower Threat Defense) softwareAffected if The device is not running Cisco Secure FTD
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Verify Snort inspection is enabledAccess the FTD management interface (FDM or FMC) and check the access control policy to confirm Snort inspection is active on the relevant policy. Use 'show inspection' or review the inspection configuration in the access control rules.Affected if Snort inspection is not enabled or not applied to the traffic policy in question
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Check the FTD software versionRun 'show version' on the FTD CLI or check the device dashboard to obtain the installed FTD version numberAffected if The installed version falls within the affected version range for this CVE (compare against Cisco's published vulnerable version list for CVE-2026-20007)
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Confirm Snort 2 or Snort 3 is in useCheck the inspection configuration or run 'show snort' to determine which Snort version (Snort 2 or Snort 3) is configured for the affected inspection policyAffected if Either Snort 2 or Snort 3 inspection engine is active on the FTD device
The environment is affected if the device is running Cisco Secure FTD with Snort inspection enabled and the installed FTD version matches the vulnerable version range for CVE-2026-20007
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataApply Cisco's published firmware update for FTD software that addresses this Snort integration logic flaw; until then, implement additional network-layer filtering as a compensating control.
Fix this in Secure Firewall Threat Defense
Scoped from the published advisory
- Consultation2.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,480.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-20007 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-20007 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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