Secure Firewall Threat DefenseApplication · Cisco
CVE-2020-3563
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 packet processing functionality 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. The vulnerability is due to inefficient memory management. An attacker could exploit this vulnerability by sending a large number of TCP packets to a specific port on an affected device. A successful exploit could allow the attacker to exhaust system memory, which could cause the device to reload unexpectedly. No manual intervention is needed to recover the device after it has reloaded.
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 confidenceA vulnerability in the packet processing functionality of Cisco Firepower Threat Defense (FTD) Software allows an unauthenticated, remote attacker to cause denial of service by sending a large number of TCP packets to a specific port. The vulnerability stems from inefficient memory management, which can be exploited to exhaust system memory and cause unexpected device reloads.
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
>= 6.3.0, < 6.3.0.6>= 6.4.0, < 6.4.0.10>= 6.5.0, < 6.5.0.5CVSS 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 checksWork through these to decide whether this CVE applies to you.
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Identify FTD software versionLog into the FTD device CLI and run the command 'show version' or 'show version | include Version' to display the installed software versionAffected if The displayed version falls within 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
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Verify FTD is exposed to networkConfirm that the FTD device has accessible TCP interfaces by reviewing the interface configuration with 'show interface' or checking the access control policy to identify exposed portsAffected if Any TCP port on the FTD device is directly accessible from untrusted networks without upstream filtering
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Check for memory exhaustion indicatorsRun 'show memory' or 'show system resource memory' in the FTD CLI to review current memory utilization patternsAffected if Memory usage is abnormally high or shows symptoms of exhaustion not attributable to normal traffic loads
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Review for unexpected reloadsExecute 'show crashinfo' or 'show reload history' to check for any unexpected device reloads or crashesAffected if The device has experienced unexplained reloads or crash events that coincide with periods of high TCP traffic to specific ports
A user is affected if their FTD software version is 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 the device has TCP ports exposed to network traffic.
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 data6.3.0.66.4.0.106.5.0.5
Apply the vendor-supplied patch for CVE-2020-3563 when available. If no patch exists, consider implementing network-level filtering or rate limiting for the affected TCP ports to mitigate the packet flood attack vector.
Fix this in Secure Firewall Threat Defense
Scoped from the published advisory
- Consultation2.0 h
- Implementation4.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,560.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-3563 — 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-2020-3563 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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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.
- 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
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