CVE-2017-12237 Cisco IOS and IOS XE Software Internet Key Exchange Denial-of-Service

Exploited in the wild High 7.5 Published 28 Sep 2017 Updated 12 Jan 2026

Remote attackers can cause denial of service on Cisco IOS devices by sending specific IKEv2 packets when ISAKMP is enabled.

Exploited in the wild: Since 3 Mar 2022
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2017-12237?

CVE-2017-12237 is a high-severity denial of service vulnerability in Cisco Ios, published on 28 Sep 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

A vulnerability in the Internet Key Exchange Version 2 (IKEv2) module of Cisco IOS 15.0 through 15.6 and Cisco IOS XE 3.5 through 16.5 could allow an unauthenticated, remote attacker to cause high CPU utilization, traceback messages, or a reload of an affected device that leads to a denial of service (DoS) condition. The vulnerability is due to how an affected device processes certain IKEv2 packets. An attacker could exploit this vulnerability by sending specific IKEv2 packets to an affected device to be processed. A successful exploit could allow the attacker to cause high CPU utilization, traceback messages, or a reload of the affected device that leads to a DoS condition. This vulnerability affects Cisco devices that have the Internet Security Association and Key Management Protocol (ISAKMP) enabled. Although only IKEv2 packets can be used to trigger this vulnerability, devices that are running Cisco IOS Software or Cisco IOS XE Software are vulnerable when ISAKMP is enabled. A device does not need to be configured with any IKEv2-specific features to be vulnerable. Many features use IKEv2, including different types of VPNs such as the following: LAN-to-LAN VPN; Remote-access VPN, excluding SSL VPN; Dynamic Multipoint VPN (DMVPN); and FlexVPN. Cisco Bug IDs: CSCvc41277.

Weakness: CWE-399

Which versions are affected by CVE-2017-12237?

It affects 2 products.

Products include Cisco Ios, Cisco Ios Xe.

How do I fix CVE-2017-12237?

No fix has been published for CVE-2017-12237 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 24 Mar 2022.

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-2017-12237 being exploited?

Yes. Attackers have exploited CVE-2017-12237 in the wild since at least 3 Mar 2022.

All Cisco Ios vulnerabilities

Sources

Also known as GHSA-pcwh-xxqr-qw2j.