Summary

• A vulnerability in the Internet Key Exchange version 2 (IKEv2) feature of Cisco IOS Software, Cisco IOS XE Software, Cisco Secure Firewall Adaptive Security Appliance (ASA) Software, and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to trigger a memory leak, resulting in a denial of service (DoS) condition on an affected device.

  This vulnerability is due to improper parsing of IKEv2 packets. An attacker could exploit this vulnerability by sending crafted IKEv2 packets to an affected device. A successful exploit of Cisco IOS Software and IOS XE Software could allow the attacker to cause the affected device to reload, resulting in a DoS condition. A successful exploit of Cisco Secure Firewall ASA Software and Secure FTD Software could allow the attacker to partially exhaust system memory, resulting in system instability, such as the inability to establish new IKEv2 VPN sessions. A manual reboot of the device is required to recover from this condition.

  Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

  This advisory is available at the following link:
  https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asa-ftd-ios-dos-kPEpQGGK

  This advisory is part of the March 2026 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: March 2026 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication.

Affected Products

• Vulnerable Products

  This vulnerability affects the following Cisco products if they have the IKEv2 VPN feature, including G-IKEv2, enabled:

  • IOS Software
  • IOS XE Software
  • Secure Firewall ASA Software
  • Secure FTD Software

  For information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory.

  Determine the IKEv2 Configuration on a Device That Is Running Cisco IOS Software or IOS XE Software

  To determine whether IKEv1 or IKEv2 is enabled on a device that is running Cisco IOS Software or IOS XE Software and, subsequently, whether IKEv2 is actively being used by the device, use the following two-step method.

  Step 1. Determine Whether IKE (v1 or v2) Is Enabled

  To determine whether IKE processing is enabled on a device, use the show ip socket | include 500 or show udp | include 500 EXEC command in the CLI. If UDP port 500 or 4500 is open on a device, the device is processing IKE packets.

  Note: If IKEv1 or IKEv2 is enabled, UDP port 500, 4500, or both will be open because both of the protocols use these ports.

  The following example shows the output of the show udp | include 500 command on a device that is processing IKE packets on UDP ports 500 and 4500, which are listening on either IPv4 or IPv6:

  Router#show udp | include 500
   17       --listen--          192.168.1.10      500   0   0 2001011   0 
   17(v6)   --listen--          --any--           500   0   0 2020011   0 
   17       --listen--          192.168.1.10     4500   0   0 2001011   0 
   17(v6)   --listen--          --any--          4500   0   0 2020011   0 

  If this command returns empty output, the device is not affected by this vulnerability. If the command returns output, proceed to Step 2.

  Step 2. Determine Whether IKEv2 Is Being Used

  To determine whether IKEv2 is actively being used by the device, use the show crypto map EXEC command in the device CLI. If a crypto map has an IKEv2 Profile associated with it, it uses IKEv2. If at least one interface is using that crypto map, the map is active.

  The following example shows the output of the show crypto map command on a device that is processing IKEv2 packets. In the output, crypto map CMAP2 is configured to use an IKEv2 Profile, profile1, and is enabled on the GigabitEthernet2 interface:

  Router2#show crypto map
  Crypto Map IPv4 "CMAP2" 10 ipsec-isakmp
          Peer = 192.168.1.200
          IKEv2 Profile: profile1
          Access-List SS dynamic: False
          Extended IP access list 120
              access-list 120 permit ip 192.168.21.0 0.0.0.255 192.168.22.0 0.0.0.255
          Current peer: 192.168.1.200
          Security association lifetime: 4608000 kilobytes/3600 seconds
          Dualstack (Y/N): N
  
          Responder-Only (Y/N): N
          PFS (Y/N): N
          Mixed-mode : Disabled
          Transform sets={ 
                  AESSET:  { esp-256-aes esp-sha256-hmac  } , 
          }
          Interfaces using crypto map CMAP2:
                  GigabitEthernet2
  Router2#

  This device is affected by this vulnerability.

  Determine the IKEv2 Configuration on a Device That Is Running Cisco Secure Firewall ASA Software or Secure FTD Software

  To determine whether IKEv2 is enabled on a device that is running Cisco Secure Firewall ASA Software or Secure FTD Software, use the show running-config crypto ikev2 | include enable CLI command. If the 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:

  firewall# show running-config crypto ikev2 | include enable
  crypto ikev2 enable outside client-services port 443

  This device is affected by this vulnerability.

  If the show running-config crypto ikev2 | include enable command returns empty output, the device is not affected by this vulnerability. 

  Products Confirmed Not Vulnerable

  Only products listed in the Vulnerable Products 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
  • NX-OS Software
  • Secure Firewall Management Center (FMC) Software

Workarounds

• There are no workarounds that address this vulnerability.

Fixed Software

• Cisco considers any workarounds and mitigations (if applicable) to be temporary solutions until an upgrade to a fixed software release is available. To fully remediate this vulnerability and avoid future exposure as described in this advisory, Cisco strongly recommends that customers upgrade to the fixed software indicated in this advisory.

  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. 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 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:

  1. Choose which advisories the tool will search—only this advisory, only advisories with a Critical or High Security Impact Rating (SIR), or all advisories.
  2. Enter a release number—for example, 15.9(3)M2 or 17.3.3.
  3. Click Check.

   

  Only this advisory All Critical and High advisories All advisories

   

  Cisco Secure Firewall ASA, Secure FMC, and Secure FTD Software

  To help customers determine their exposure to vulnerabilities in Cisco Secure Firewall ASA, Secure FMC, and Secure FTD Software, Cisco provides the Cisco Software Checker. 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 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:

  1. Choose which advisories the tool will search—all advisories, only advisories with a Critical or High Security Impact Rating (SIR), or only this advisory.
  2. Choose the appropriate software.
  3. Choose the appropriate platform.
  4. Enter a release number—for example, 9.20.3.4 for Cisco Secure Firewall ASA Software or 7.4.2 for Cisco Secure FTD Software.
  5. 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 Secure Firewall 1200 Series Secure Firewall 3100 Series Secure Firewall 4200 Series

   

  Additional Resources

  For help determining the best Cisco Secure Firewall ASA, Secure FMC, or Secure FTD Software release, see the following Recommended Releases documents. If a security advisory recommends a later release, Cisco recommends following the advisory guidance.

  Cisco Secure Firewall ASA Compatibility
  Cisco Secure Firewall ASA Upgrade Guide
  Cisco Secure Firewall Threat Defense Compatibility Guide

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.

Source

• This vulnerability was found during internal security testing by Jason Crowder of the Cisco Advanced Security Initiatives Group (ASIG).

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asa-ftd-ios-dos-kPEpQGGK

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	—	Final	2026-MAR-25

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