CVE-2021-1620 Cisco IOS and IOS XE Software IKEv2 AutoReconnect Feature Denial of Service Vulnerability

High 7.7 Published 23 Sep 2021 Updated 7 Nov 2024

An authenticated remote attacker can exhaust IP addresses in the local pool via IKEv2 AutoReconnect, causing a denial of service.

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

What is CVE-2021-1620?

CVE-2021-1620 is a high-severity denial of service vulnerability in Cisco Ios, published on 23 Sep 2021. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

A vulnerability in the Internet Key Exchange Version 2 (IKEv2) support for the AutoReconnect feature of Cisco IOS Software and Cisco IOS XE Software could allow an authenticated, remote attacker to exhaust the free IP addresses from the assigned local pool. This vulnerability occurs because the code does not release the allocated IP address under certain failure conditions. An attacker could exploit this vulnerability by trying to connect to the device with a non-AnyConnect client. A successful exploit could allow the attacker to exhaust the IP addresses from the assigned local pool, which prevents users from logging in and leads to a denial of service (DoS) condition.

Weakness: CWE-772, CWE-563

Which versions are affected by CVE-2021-1620?

It affects 2 products.

Products include Cisco Ios, Cisco Ios Xe.

How do I fix CVE-2021-1620?

No fix has been published for CVE-2021-1620 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-2021-1620 being exploited?

There is no known exploitation of CVE-2021-1620 in the wild and no public exploit code.

All Cisco Ios vulnerabilities

Sources

Also known as GHSA-hj64-pmxg-fcx3.