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Secure Firewall Threat DefenseApplication · Cisco

CVE-2020-3571

HIGH · 8.6 CVSS v3.1 Published 2020-10-21
Fix available
A fix is available. Upgrade to 6.3.0.6 / 6.4.0.10 or later.
See remediation →
95/100
Remediation priority · Urgent
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 ICMP ingress packet processing of Cisco Firepower Threat Defense (FTD) Software for Cisco Firepower 4110 appliances could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to incomplete input validation upon receiving ICMP packets. An attacker could exploit this vulnerability by sending a high number of crafted ICMP or ICMPv6 packets to an affected device. A successful exploit could allow the attacker to cause a memory exhaustion condition that may result in an unexpected reload. No manual intervention is needed to recover the device after the reload.

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 ICMP ingress packet processing of Cisco Firepower Threat Defense (FTD) Software allows unauthenticated remote attackers to cause memory exhaustion by sending crafted ICMP/ICMPv6 packets to affected devices, resulting in unexpected reloads.

MitigationApply the Cisco FTD software update addressing CVE-2020-3571. Until patched, consider implementing ICMP rate limiting or filtering at network perimeter to reduce attack surface.

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, < 6.3.0.6>= 6.4.0, < 6.4.0.10>= 6.5.0, < 6.5.0.5

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
Changed
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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 FTD software version
    Log into the FTD device CLI and run the command 'show version' or 'show running-config | include version' to retrieve the installed software version
    Affected if The displayed version falls within any of these ranges: 6.3.0 through 6.3.0.5, 6.4.0 through 6.4.0.9, or 6.5.0 through 6.5.0.4
  2. Confirm the device is running Cisco FTD
    From the CLI output of 'show version', verify the product name in the output is Cisco Firepower Threat Defense or FTD
    Affected if The device is Cisco FTD software
  3. Verify ICMP processing is enabled
    Check the FTD configuration using 'show running-config icmp' or 'show running-config | include icmp' to see if ICMP traffic inspection is configured on any interfaces
    Affected if ICMP inspection or ICMP access lists are configured, allowing ICMP traffic to reach the FTD device
  4. Check interface exposure to untrusted networks
    Use 'show interface' and 'show running-config interface' commands to identify which interfaces have IP addresses and are accessible from external/untrusted networks
    Affected if The FTD device has interfaces with public-facing or untrusted network exposure that can receive ICMP packets directly

The device is affected if it runs Cisco FTD software version 6.3.0.x before 6.3.0.6, 6.4.0.x before 6.4.0.10, or 6.5.0.x before 6.5.0.5, and has ICMP-accessible interfaces on untrusted networks.

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.

From vendor data
Upgrade available Upgrade to 6.3.0.6 / 6.4.0.10 / 6.5.0.5 or later
Fixed in 6.3.0.66.4.0.106.5.0.5
Interim mitigation

Apply the Cisco FTD software update addressing CVE-2020-3571. Until patched, consider implementing ICMP rate limiting or filtering at network perimeter to reduce attack surface.

Fix this in Secure Firewall Threat Defense Scoped from the published advisory
  • Consultation4.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,970
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Scan for this in your stack

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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-2020-3571 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