CVE-2020-3563

Cisco Firepower Threat Defense Software TCP Flood Denial of Service Vulnerability

HIGH
8.6
CVSS Score
Published: October 21, 2020 at 06:41 PM UTC
Updated: August 11, 2026 at 07:33 PM UTC
1 product affected across 1 vendorSecure Firewall Threat Defense

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Severity
HIGH8.6
Exploit prediction
EPSS 1%
SSVC
No known exploit

Description

A 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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

6.3.0 ≤ v < 6.3.0.66.4.0 ≤ v < 6.4.0.106.5.0 ≤ v < 6.5.0.5

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-400

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