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CVE-2017-12237

KEVCisco IOS and IOS XE Software Internet Key Exchange Denial-of-Service Vulnerability

A vulnerability in the Internet Key Exchange Version 2 (IKEv2) module of Cisco IOS and Cisco IOS XE 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.

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.

CVSS 3.1 vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
PublishedSep 29, 2017
Last modifiedJun 17, 2026
Added to KEVMar 3, 2022
Remediation dueMar 24, 2022
    68
    Risk assessment · High

    Actively exploited. Patch immediately.

    Exploitation
    Confirmed in the wild (CISA KEV)
    Federal remediation deadline
    Overdue by 1678 days
    CVSS
    7.5 HIGH
    EPSS (30-day exploit probability)
    7.1% · top 6% of all CVEs
    Weakness
    CWE-399
    Attack vector
    Network, remotely reachable
    Preconditions
    No privileges and no user interaction
    1. 1.Apply updates per vendor instructions.
    2. 2.Treat as emergency change: patch or isolate internet-facing instances first.
    3. 3.Review exposure: confirm which instances are reachable from the internet and restrict access until patched.
    4. 4.Hunt for compromise: review logs for the disclosure window, not just from the patch date.

    Assessment is derived automatically from the live signals above; verify against your own asset inventory.