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Secure Firewall Threat DefenseApplication · Cisco

CVE-2022-20946

HIGH · 7.5 CVSS v3.1 Published 2022-11-15
Fix available
A fix is available. Upgrade to after 7.0.3 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 generic routing encapsulation (GRE) tunnel decapsulation feature of Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to a memory handling error that occurs when GRE traffic is processed. An attacker could exploit this vulnerability by sending a crafted GRE payload through an affected device. A successful exploit could allow the attacker to cause the device to restart, resulting in a DoS condition. https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-gre-dos-hmedHQPM ["https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-gre-dos-hmedHQPM"] This advisory is part of the November 2022 release of the Cisco ASA, FTD, and FMC Security Advisory Bundled publication.

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 memory handling error in Cisco FTD's GRE tunnel decapsulation feature allows an unauthenticated remote attacker to send a crafted GRE payload through the affected device, causing it to restart and result in a DoS condition.

MitigationApply the Cisco-provided software update/patch for FTD. If GRE is not required, disable GRE tunnel processing or implement ACLs to filter untrusted GRE traffic at network boundaries.

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:>= 6.3.0, <= 6.3.0.5>= 6.4.0, <= 6.4.0.15>= 6.5.0, <= 6.5.0.5>= 6.6.0, <= 6.6.5.2>= 6.7.0, <= 6.7.0.3>= 7.0.0, <= 7.0.3= 7.1.0.0= 7.1.0.1= 7.1.0.2

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. Identify the device as Cisco FTD
    Confirm the device is running Cisco Firepower Threat Defense (FTD) by checking the system version or device model. On the FTD CLI, run 'show version' or check the management interface for the device type.
    Affected if The device is not Cisco FTD (for example, it is ASA, Firepower Management Center, or a different platform)
  2. Determine the installed FTD version
    On the FTD CLI, run 'show version' and locate the software version string (for example, 6.4.0.10). Compare this version against the affected ranges: 6.3.0-6.3.0.5, 6.4.0-6.4.0.15, 6.5.0-6.5.0.5, 6.6.0-6.6.5.2, 6.7.0-6.7.0.3, 7.0.0-7.0.3, 7.1.0.0-7.1.0.2.
    Affected if The installed version falls within any of the listed affected version ranges
  3. Verify if GRE tunnel decapsulation is configured
    On the FTD CLI, run 'show run | include gre' to check for GRE tunnel configuration. Also check interface configurations for any GRE tunnel interfaces using 'show interface' or 'show run interface'.
    Affected if GRE tunnels are configured and the device is processing GRE decapsulation traffic

The device is affected if it runs Cisco FTD within versions 6.3.0 through 7.1.0.2 and has GRE tunnel decapsulation actively configured or processing traffic.

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 a release after 7.0.3
Interim mitigation

Apply the Cisco-provided software update/patch for FTD. If GRE is not required, disable GRE tunnel processing or implement ACLs to filter untrusted GRE traffic at network boundaries.

Recommended fix Moderate confidence

FTD 6.3.0.6+, 6.4.0.16+, 6.5.0.6+, or 6.6.6+ (depending on your major version branch)

  1. 1. Identify the current FTD version by running 'show version' on the device
  2. 2. Determine which upgrade path applies based on your current version (6.3.x, 6.4.x, 6.5.x, or 6.6.x)
  3. 3. For FTD 6.3.x: Upgrade to version 6.3.0.6 or later
  4. 4. For FTD 6.4.x: Upgrade to version 6.4.0.16 or later
  5. 5. For FTD 6.5.x: Upgrade to version 6.5.0.6 or later
  6. 6. For FTD 6.6.x: Upgrade to version 6.6.6 or later
  7. 7. Download the appropriate FTD upgrade package from Cisco's Software Download center
  8. 8. Upload the upgrade package to the device using 'upgrade', 'reboot', or via FMC/FDO management interface
Caveat Upgrading FTD may require compatible FMC version; ensure FMC-FTD version compatibility before upgrading

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
  • Implementation6.0 h
  • Testing8.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,800
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,080.

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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-2022-20946 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