Summary

• A vulnerability in the Network-Based Application Recognition (NBAR) feature of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload, causing a denial of service (DoS) condition.

  This vulnerability is due to improper handling of malformed Control and Provisioning of Wireless Access Points (CAPWAP) packets. An attacker could exploit this vulnerability by sending malformed CAPWAP packets through an affected device. A successful exploit could allow the attacker to cause the device to reload unexpectedly, resulting in a DoS condition.

  Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. However, there is a mitigation.

  This advisory is available at the following link:
  https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-nbar-dos-LAvwTmeT

  This advisory is part of the September 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: September 2025 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication.

Affected Products

• Vulnerable Products

  This vulnerability affects the following Cisco products if they are running a vulnerable release of Cisco IOS XE Software and have the NBAR for CAPWAP feature enabled:

  • 1100 Integrated Services Routers
  • 4000 Series Integrated Services Routers
  • ASR 920 Series Aggregation Services Routers
  • ASR 1000 Series Aggregation Services Routers
  • Catalyst 1101 Rugged Routers
  • Catalyst 8000V Edge Software
  • Catalyst 8200 Series Edge Platforms
  • Catalyst 8300 Series Edge Platforms
  • Catalyst 8500 Edge Platforms
  • Catalyst 8500L Edge Platforms
  • Catalyst IR8300 Rugged Series Routers 

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

  Determine the Device Configuration

  To determine whether the device has the CAPWAP inspection for NBAR enabled, use the show running-config | include tunneled-traffic capwap CLI command. If there is output for this command, CAPWAP inspection for NBAR is enabled, as shown in following example:

  Router#show running-config | include tunneled-traffic capwap
  ip nbar classification tunneled-traffic capwap
  Router#

  If there is no output, the device is not affected by this vulnerability.

  Otherwise, determine whether NBAR is in use on a device by verifying that the show ip nbar control-plane | include NBAR state CLI command reports the state as ACTIVATED. If that command does not produce output, or it reports the state as DEACTIVATED, then NBAR operation is not configured.

  The following example shows the output of a device that has NBAR is enabled:

  Router#show ip nbar control-plane | include NBAR state
  NBAR state is ACTIVATED
  NBAR state: ACTIVATED

  The following example shows the output of a device that has NBAR disabled:

  Router#show ip nbar control-plane | include NBAR state
  NBAR state is DEACTIVATED
  NBAR state: DEACTIVATED

  If both CAPWAP inspection for NBAR is enabled and NBAR is ACTIVATED, the device is considered vulnerable.

  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 Software
  • IOS XR Software
  • NX-OS Software

Workarounds

• There are no workarounds that address this vulnerability. However, as a mitigation, CAPWAP inspection for NBAR can be disabled using the global configuration CLI command no ip nbar classification tunneled-traffic capwap.

  While this mitigation has been deployed and was proven successful in a test environment, customers should determine the applicability and effectiveness in their own environment and under their own use conditions. Customers should be aware that any workaround or mitigation that is implemented may negatively impact the functionality or performance of their network based on intrinsic customer deployment scenarios and limitations. Customers should not deploy any workarounds or mitigations before first evaluating the applicability to their own environment and any impact to such environment.

Fixed Software

• Cisco considers any workarounds and mitigations 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

   

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 the resolution of a Cisco TAC support case.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-nbar-dos-LAvwTmeT

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	—	Final	2025-SEP-24

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