CVE-2020-3554: Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software Denial of Service Vulnerability

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 2.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2020-10-21 · updated 2026-08-11
Weakness: CWE-400

Description

A vulnerability in the TCP packet processing of Cisco Adaptive Security Appliance (ASA) Software and 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 a memory exhaustion condition. An attacker could exploit this vulnerability by sending a high rate of crafted TCP traffic through an affected device. A successful exploit could allow the attacker to exhaust device resources, resulting in a DoS condition for traffic transiting the affected device.

Affected products

Cisco Adaptive Security Appliance: before 9.12.4.3 — fixed in 9.12.4.3
Cisco ASA Software: from 9.13.0 before 9.13.1.13; from 9.14.0 before 9.14.1.30 — fixed in 9.13.1.13, 9.14.1.30
Cisco Firepower Threat Defense Software: through 6.2.2; from 6.3.0 before 6.4.0.10; from 6.5.0 before 6.5.0.5; 6.6.0 — fixed in 6.4.0.10, 6.5.0.5

How to fix

Upgrade to a fixed version: Cisco Adaptive Security Appliance 9.12.4.3; Cisco ASA Software 9.13.1.13, 9.14.1.30; Cisco Firepower Threat Defense Software 6.4.0.10, 6.5.0.5. Check the vendor advisory for mitigations.

References

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