CVE-2020-3421 Cisco IOS XE Software Zone-Based Firewall Denial of Service Vulnerabilities

High 8.6 Published 24 Sep 2020 Updated 13 Nov 2024

Remote attackers can cause Cisco IOS XE devices to reload or stop forwarding traffic by sending specific Layer 4 packet sequences.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2020-3421?

CVE-2020-3421 is a high-severity denial of service vulnerability in Cisco Ios Xe, published on 24 Sep 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Multiple vulnerabilities in the Zone-Based Firewall feature of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause the device to reload or stop forwarding traffic through the firewall. The vulnerabilities are due to incomplete handling of Layer 4 packets through the device. An attacker could exploit these vulnerabilities by sending a certain sequence of traffic patterns through the device. A successful exploit could allow the attacker to cause the device to reload or stop forwarding traffic through the firewall, resulting in a denial of service. For more information about these vulnerabilities, see the Details section of this advisory.

Weakness: CWE-754

Which versions are affected by CVE-2020-3421?

It affects 1 product.

Products include Cisco Ios Xe.

How do I fix CVE-2020-3421?

No fix has been published for CVE-2020-3421 yet. Limit exposure of the affected software until one is available.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2020-3421 being exploited?

There is no known exploitation of CVE-2020-3421 in the wild and no public exploit code.

All Cisco Ios Xe vulnerabilities

Sources

Also known as GHSA-9gg8-xvhp-2q7g.