Summary: A vulnerability in the Internet Key Exchange version 2 (IKEv2) protocol processing of Cisco Adaptive Security Appliance (ASA) Software, Cisco Firepower Threat Defense (FTD) Software, Cisco IOS Software, and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to insufficient input validation when processing IKEv2 messages. An attacker could exploit this vulnerability by sending crafted IKEv2 traffic to an affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition on the affected device. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. This advisory is part of the May 2025 release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: May 2025 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication ["https://sec.cloudapps.cisco.com/security/center/viewErp.x?alertId=ERP-75279"].

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Vulnerable Products: This vulnerability affects Cisco products if they are running a vulnerable release of Cisco ASA, FTD, IOS, or IOS XE Software and have the IKEv2 protocol enabled. Note: G-IKEv2 is not affected by this vulnerability. For information about which Cisco software releases are vulnerable, see the Fixed Software ["#fs"] section of this advisory. Determine the Cisco ASA or FTD Software IKEv2 Configuration To determine whether IKEv2 is enabled on an interface, use the show running-config crypto ikev2 | include enable CLI command. If that command returns output, IKEv2 is enabled on at least one interface. The following example shows the output of the show running-config crypto ikev2 | include enable command on a device that has IKEv2 enabled on the outside interface: device# show running-config crypto ikev2 | include enable crypto ikev2 enable outside If the command returns no output, the device is not affected by this vulnerability. Note: For devices that are running Cisco FTD Software, the command prompt will end with > and not #. Determine the Cisco IOS or IOS XE Software IKEv2 Configuration 1. Determine Whether the Device Is Configured with IKE (v1 or v2) To determine whether IKE processing is enabled, use the show ip sockets or show udp EXEC command in the CLI. These commands will show the same output for both IKEv1 and IKEv2 because both use the same port numbers. If UDP port 500, UDP port 848, UDP port 4500, or UDP port 4848 is open on a device, the device is processing IKE packets. The following example shows the output of the show udp command on a device that is processing IKE packets on UDP port 500 and UDP port 4500, using either IPv4 or IPv6: router# show udp Proto Remote Port Local Port In Out Stat TTY OutputIF 17 --listen-- 192.168.130.21 500 0 0 1001011 0 17(v6) --listen-- UNKNOWN 500 0 0 1020011 0 17 --listen-- 192.168.130.21 4500 0 0 1001011 0 17(v6) --listen-- UNKNOWN 4500 0 0 1020011 0 . . . router# If the command returns no output, or the command returns an error, then the device is not affected by this vulnerability. If the device returns output for any of the mentioned UDP ports for IKE, proceed to the next step. 2. Determine Whether the IKE Configuration of the Device Is Using IKEv2 If the show udp command shows that the device is listening for IKE traffic, to assess whether the device is configured to use IKEv2, enter the CLI command show running-config | include ikev2. If the command returns output, the configuration is most likely set up to process IKEv2 traffic and is therefore affected by this vulnerability. Note: Some customers may have entered IKEv2 commands without associating them with appropriate features. Reviewing the full configuration or examining the output of the various show crypto ikev2 CLI commands can help determine whether IKEv2 is properly configured.

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Products Confirmed Not Vulnerable: Only products listed in the Vulnerable Products ["#vp"] section of this advisory are known to be affected by this vulnerability. Cisco has confirmed that this vulnerability does not affect the following Cisco products: IOS XR Software Meraki products NX-OS Software Secure Firewall Management Center (FMC) Software, formerly Firepower Management Center Software

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Workarounds: There are no workarounds that address this vulnerability.

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Fixed Software: Cisco has released free software updates ["https://sec.cloudapps.cisco.com/security/center/resources/security_vulnerability_policy.html#ssu"] that address the vulnerability described in this advisory. Customers with service contracts that entitle them to regular software updates should obtain security fixes through their usual update channels. Customers may only install and expect support for software versions and feature sets for which they have purchased a license. By installing, downloading, accessing, or otherwise using such software upgrades, customers agree to follow the terms of the Cisco software license: https://www.cisco.com/c/en/us/products/end-user-license-agreement.html ["https://www.cisco.com/c/en/us/products/end-user-license-agreement.html"] Additionally, customers may only download software for which they have a valid license, procured from Cisco directly, or through a Cisco authorized reseller or partner. In most cases this will be a maintenance upgrade to software that was previously purchased. Free security software updates do not entitle customers to a new software license, additional software feature sets, or major revision upgrades. The Cisco Support and Downloads page ["https://www.cisco.com/c/en/us/support/index.html"] on Cisco.com provides information about licensing and downloads. This page can also display customer device support coverage for customers who use the My Devices tool. When considering software upgrades ["https://sec.cloudapps.cisco.com/security/center/resources/security_vulnerability_policy.html#fixes"], customers are advised to regularly consult the advisories for Cisco products, which are available from the Cisco Security Advisories page ["https://www.cisco.com/go/psirt"], to determine exposure and a complete upgrade solution. In all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, customers are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers. Customers Without Service Contracts Customers who purchase directly from Cisco but do not hold a Cisco service contract and customers who make purchases through third-party vendors but are unsuccessful in obtaining fixed software through their point of sale should obtain upgrades by contacting the Cisco TAC: https://www.cisco.com/c/en/us/support/web/tsd-cisco-worldwide-contacts.html ["https://www.cisco.com/c/en/us/support/web/tsd-cisco-worldwide-contacts.html"] Customers should have the product serial number available and be prepared to provide the URL of this advisory as evidence of entitlement to a free upgrade. Cisco ASA, FMC, and FTD Software To help customers determine their exposure to vulnerabilities in Cisco ASA, FMC, and FTD Software, Cisco provides the Cisco Software Checker ["https://sec.cloudapps.cisco.com/security/center/softwarechecker.x"]. This tool identifies any Cisco security advisories that impact a specific software release and the earliest release that fixes the vulnerabilities that are described in each advisory (“First Fixed”). If applicable, the tool also returns the earliest release that fixes all the vulnerabilities that are described in all the advisories that the Software Checker identifies (“Combined First Fixed”). To use the tool, go to the Cisco Software Checker ["https://sec.cloudapps.cisco.com/security/center/softwarechecker.x"] page and follow the instructions. Alternatively, use the following form to search for vulnerabilities that affect a specific software release. To use the form, follow these steps: Choose which advisories the tool will search—all advisories, only advisories with a Critical or High Security Impact Rating (SIR) ["https://sec.cloudapps.cisco.com/security/center/resources/security_vulnerability_policy.html#asr"], or only this advisory. Choose the appropriate software. Choose the appropriate platform. Enter a release number—for example, 9.16.2.11 for Cisco ASA Software or 6.6.7 for Cisco FTD Software. Click Check. Only this advisory All Critical and High advisories All advisories Cisco ASA Software Cisco FMC Software Cisco FTD Software Any Platform 3000 Series Industrial Security Appliances (ISA) ASA 5500-X Series Firewalls ASA Service Module Adaptive Security Virtual Appliance (ASAv) Firepower 1000 Series Firepower 2100 Series Firepower 4100 Series Firepower 9000 Series Firepower NGFW Virtual Secure Firewall 3100 Series Firepower Management Center Appliances For instructions on upgrading a Cisco FTD device, see the appropriate Cisco FMC upgrade guide ["https://www.cisco.com/c/en/us/support/security/defense-center/products-installation-guides-list.html"]. Cisco IOS and IOS XE Software To help customers determine their exposure to vulnerabilities in Cisco IOS and IOS XE Software, Cisco provides the Cisco Software Checker ["https://sec.cloudapps.cisco.com/security/center/softwarechecker.x"]. This tool identifies any Cisco security advisories that impact a specific software release and the earliest release that fixes the vulnerabilities that are described in each advisory (“First Fixed”). If applicable, the tool also returns the earliest release that fixes all the vulnerabilities that are described in all the advisories that the Software Checker identifies (“Combined First Fixed”). To use the tool, go to the Cisco Software Checker ["https://sec.cloudapps.cisco.com/security/center/softwarechecker.x"] page and follow the instructions. Alternatively, use the following form to determine whether a release is affected by any Cisco Security Advisory. To use the form, follow these steps: Choose which advisories the tool will search—only this advisory, only advisories with a Critical or High Security Impact Rating (SIR) ["https://sec.cloudapps.cisco.com/security/center/resources/security_vulnerability_policy.html#asr"], or all advisories. Enter a release number—for example, 15.9(3)M2 or 17.3.3. Click Check. Only this advisory All Critical and High advisories All advisories

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Vulnerability Policy: To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy ["http://www.cisco.com/web/about/security/psirt/security_vulnerability_policy.html"]. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.

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Exploitation and Public Announcements: The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.

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Source: Cisco would like to thank the U.S. National Security Agency (NSA) for reporting this vulnerability.

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