CVE-2022-20837 Cisco IOS XE Software DNS NAT Protocol Application Layer Gateway Denial of Service Vulnerability
Remote attackers can cause a reload and denial of service on Cisco IOS XE devices by sending crafted TCP DNS packets through NAT-enabled interfaces.
- 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-2022-20837?
CVE-2022-20837 is a high-severity denial of service vulnerability in Cisco Ios Xe, published on 10 Oct 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A vulnerability in the DNS application layer gateway (ALG) functionality that is used by Network Address Translation (NAT) in Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload. This vulnerability is due to a logic error that occurs when an affected device inspects certain TCP DNS packets. An attacker could exploit this vulnerability by sending crafted DNS packets through the affected device that is performing NAT for DNS packets. A successful exploit could allow the attacker to cause the device to reload, resulting in a denial of service (DoS) condition on the affected device. Note: This vulnerability can be exploited only by sending IPv4 TCP packets through an affected device. This vulnerability cannot be exploited by sending IPv6 traffic.
Weakness: CWE-754
Which versions are affected by CVE-2022-20837?
It affects 1 product.
Products include Cisco Ios Xe.
How do I fix CVE-2022-20837?
No fix has been published for CVE-2022-20837 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-2022-20837 being exploited?
There is no known exploitation of CVE-2022-20837 in the wild and no public exploit code.
Other vulnerabilities in Cisco Ios Xe
- CVE-2023-20198 Cisco IOS XE Web UI Privilege Escalation
- CVE-2018-0151 Cisco IOS Software and Cisco IOS XE Software Quality of Service Remote Code Execution
- CVE-2023-20273 Cisco IOS XE Web UI Command Injection
- CVE-2025-20188 Hardcoded credentials in Cisco IOS XE Software
- CVE-2021-34770 Cisco IOS XE Software for Catalyst 9000 Family Wireless Controllers CAPWAP Remote Code Execution Vulnerability
Sources
Also known as GHSA-7cwr-j6cv-fjjp.