Summary

• A vulnerability in the packet filtering features of Cisco IOS XE SD-WAN Software could allow an unauthenticated, remote attacker to bypass Layer 3 and Layer 4 traffic filters.

  This vulnerability is due to improper traffic filtering conditions on an affected device. An attacker could exploit this vulnerability by sending a crafted packet to the affected device. A successful exploit could allow the attacker to bypass the Layer 3 and Layer 4 traffic filters and inject a crafted packet into the network.

  Cisco has released software updates that address this vulnerability. There are workarounds that address this vulnerability.

  This advisory is available at the following link:
  https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snmp-bypass-HHUVujdn

  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.

Affected Products

• Vulnerable Products

  Cisco IOS XE Software

  At the time of publication, this vulnerability affected universal Cisco IOS XE Software releases 17.2.1r and later that were running in Controller mode. Cisco IOS XE Software releases earlier than Release 17.2.1r are not affected by this vulnerability because they do not include the SD-WAN feature.

  At the time of publication, this vulnerability also affected the following standalone Cisco IOS XE SD-WAN Software releases:

  • 16.9.1 through 16.9.4
  • 16.10.1 through 16.10.5
  • 16.11.1a
  • 16.12.2r through 16.12.4

  Note: The standalone Cisco IOS XE SD-WAN release images are separate from the universal Cisco IOS XE Software releases. The SD-WAN feature set was first integrated into the universal Cisco IOS XE Software releases starting with Cisco IOS XE Software Release 17.2.1r. For more information, see the Install and Upgrade Cisco IOS XE Catalyst SD-WAN Release 17.2.1r and Later chapter of the Cisco Catalyst SD-WAN Getting Started Guide.

  Cisco IOS XE cEdge Routers

  At the time of publication, this vulnerability affected Cisco SD-WAN cEdge Routers with Simple Network Management Protocol (SNMP) enabled on the tunnel 0 interface. If SNMP is not enabled, the device is not affected by this vulnerability.

  For information about which Cisco software releases were vulnerable at the time of publication, see the Fixed Software section of this advisory.

  Determine the Device Configuration

  To determine whether a device has SNMP version 1 (SNMPv1) or Community-based SNMP version 2 (SNMPv2c) enabled, use the show running-config | include snmp-server community CLI command. If there is output, SNMP is enabled, as shown in the following example:

  Router# show running-config | include snmp-server community
  snmp-server community public ro

  To determine whether a device has SNMP version 3 (SNMPv3) enabled, use the show running-config | include snmp-server group and show snmp user CLI commands. If there is output from both commands, SNMPv3 is enabled, as shown in the following example:

  Router# show running-config | include snmp-server group
  snmp-server group v3group v3 noauth

  Router# show snmp user
  User name: remoteuser1
  Engine ID: 800000090300EE01E71C178C
  storage-type: nonvolatile     active
  Authentication Protocol: SHA
  Privacy Protocol: None
  Group-name: v3group

  
  

  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
  • Meraki
  • NX-OS Software

Workarounds

• There is a workaround that addresses this vulnerability.

  To remediate this issue, make one of the following changes from the Cisco SD-WAN Manager interface:

  • Configure an extended access control list (ACL) to block and allow specific ingress and egress traffic to and from the device. For instructions, see Configure ACL to Block/Match Traffic on cEdges with vManage Policy.
  • Configure a device access policy to be pushed down to the edge devices to block unsolicited SNMP traffic. When configuring the policy, consider that SNMPv3 authorization must happen before any response is sent to a host that sends a request. For instructions, see the Device Access Policy chapter of the Cisco Catalyst SD-WAN Policies Configuration Guide.

  If the device is not in Controller mode or the device does not have SD-WAN enabled, the device is not affected by this vulnerability.

  While this workaround 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

• When considering software upgrades, customers are advised to regularly consult the advisories for Cisco products, which are available from the Cisco Security Advisories page, 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.

  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 aware that proof-of-concept exploit code is available for the vulnerability described in this advisory.

  The Cisco PSIRT is not aware of any malicious use of the vulnerability that is described in this advisory.

Source

• Cisco would like to thank the external researcher who reported this vulnerability.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snmp-bypass-HHUVujdn

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	-	Final	2025-MAY-07

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