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Secure Firewall Threat DefenseApplication · Cisco

CVE-2022-20746

HIGH · 7.5 CVSS v3.1 Published 2022-05-03
Fix available
A fix is available. Upgrade to 6.4.0.15 / 6.6.5.2 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

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 · unedited
A vulnerability in the TCP proxy functionality of Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to trigger a denial of service (DoS) condition. This vulnerability is due to improper handling of TCP flows. An attacker could exploit this vulnerability by sending a crafted stream of TCP traffic through an affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition.

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 · high confidence

A vulnerability in the TCP proxy functionality of Cisco Firepower Threat Defense (FTD) Software allows an unauthenticated, remote attacker to send crafted TCP traffic through an affected device. Due to improper handling of TCP flows, this causes the device to reload, resulting in a denial of service condition.

MitigationApply the Cisco vendor patch for FTD when available. As an interim measure, implement network-level filtering or rate limiting for suspicious TCP traffic patterns targeting the affected device.

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
Affected:< 6.4.0.15>= 6.5.0, < 6.6.5.2>= 7.0.0, < 7.0.2= 7.1.0

CVSS 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
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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 checks

Work through these to decide whether this CVE applies to you.

  1. Confirm Cisco FTD is installed
    Log into the device CLI and run 'show version' or check the system dashboard to verify the device is running Cisco Firepower Threat Defense software.
    Affected if The device is not running Cisco FTD (this CVE only applies to FTD, not other Cisco ASA or Firepower software).
  2. Identify the FTD version
    Run the command 'show version' in the FTD CLI and locate the version string (for example, it will display as something like 6.4.0.x, 6.6.5.x, 7.0.x, or 7.1.x).
    Affected if The installed version falls within < 6.4.0.15, >= 6.5.0 < 6.6.5.2, >= 7.0.0 < 7.0.2, or equals 7.1.0.
  3. Determine if TCP proxy is configured
    Run 'show run all' or 'show configuration' in the FTD CLI and search for 'tcp proxy' or 'inspect tcp proxy' entries. Alternatively, check the access policy or intrusion policy configurations for any TCP proxy rules orinspections.
    Affected if TCP proxy functionality is explicitly enabled or configured in the device policies.
  4. Check for TCP proxy module status
    Run 'show tcp-proxy' or 'show module' commands if available, to see if the TCP proxy inspection module is loaded and active.
    Affected if The TCP proxy module shows as active or enabled in the module status.

The device is affected if it runs a vulnerable FTD version AND has TCP proxy functionality enabled or configured.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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.

dbcve · scoped
Upgrade available Upgrade to 6.4.0.15 / 6.6.5.2 / 7.0.2 or later
Fixed in 6.4.0.156.6.5.27.0.2
Interim mitigation

Apply the Cisco vendor patch for FTD when available. As an interim measure, implement network-level filtering or rate limiting for suspicious TCP traffic patterns targeting the affected device.

Recommended fix High confidence

6.4.0.15, 6.6.5.2, 7.0.2, or 7.1.1+ depending on starting branch (recommend latest stable 7.x release if possible)

  1. 1. Identify the current FTD version by navigating to System > Updates in the FTD web interface or running 'show version' in CLI
  2. 2. Determine which upgrade path applies based on current version: for 6.4.x upgrade to 6.4.0.15+, for 6.5.x-6.6.x upgrade to 6.6.5.2+, for 7.0.x upgrade to 7.0.2+, for 7.1.0 upgrade to 7.1.1+
  3. 3. Download the appropriate FTD upgrade package from Cisco Software Central (software.cisco.com)
  4. 4. Upload the upgrade package via the FTD web interface (System > Updates > Upload Update) or via CLI using 'upgrade <package>
  5. 5. Schedule a maintenance window as the device will reload during upgrade
  6. 6. Initiate the upgrade and monitor for completion
  7. 7. Verify successful upgrade by confirming the new version with 'show version' and verify TCP proxy functionality is operational
  8. 8. Test traffic flow through the device to confirm normal operation
Caveat Standard FTD upgrade considerations apply: verify compatibility with FMC version, backup configuration, ensure sufficient disk space; may require downtime for reload

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Secure Firewall Threat Defense Scoped from the published advisory
  • Consultation4.0 h
  • Implementation2.0 h
  • Testing6.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,420
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2022-20746 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data