CVE-2020-3255: A vulnerability in the packet processing functionality of Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacke...

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 high rate of IPv4 or IPv6 traffic through an affected device. This traffic would need to match a configured block action in an access control policy. An exploit could allow the attacker to cause a memory exhaustion condition on the affected device, which would result in a DoS for traffic transiting the device, as well as sluggish performance of the management interface. Once the flood is stopped, performance should return to previous states.

Metrics

CVSS 3.1

7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

1.80%

75.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Cisco	Firepower Threat Defense	>= 6.2.3, < 6.2.3.16
Cisco	Firepower Threat Defense	>= 6.3.0, < 6.3.0.6
Cisco	Firepower Threat Defense	>= 6.4.0, < 6.4.0.9
Cisco	Asa 5505 Firmware	9.10\(1.3\)
Cisco	Asa 5510 Firmware	9.10\(1.3\)
Cisco	Asa 5512-X Firmware	9.10\(1.3\)
Cisco	Asa 5515-X Firmware	9.10\(1.3\)
Cisco	Asa 5520 Firmware	9.10\(1.3\)
Cisco	Asa 5525-X Firmware	9.10\(1.3\)
Cisco	Asa 5540 Firmware	9.10\(1.3\)
Cisco	Asa 5545-X Firmware	9.10\(1.3\)
Cisco	Asa 5550 Firmware	9.10\(1.3\)
Cisco	Asa 5555-X Firmware	9.10\(1.3\)
Cisco	Asa 5580 Firmware	9.10\(1.3\)
Cisco	Asa 5585-X Firmware	9.10\(1.3\)

References

Timeline

Published: May 6, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-3255?

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 high rate of IPv4 or IPv6 traffic through an affected device. This traffic would need to match a configured block action in an access control policy. An exploit could allow the attacker to cause a memory exhaustion condition on the affected device, which would result in a DoS for traffic transiting the device, as well as sluggish performance of the management interface. Once the flood is stopped, performance should return to previous states.

How severe is CVE-2020-3255?

CVE-2020-3255 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 1.80% probability of exploitation in the next 30 days.

How do I fix CVE-2020-3255?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.