Cisco IOS XE Software for Cisco cBR-8 Converged Broadband Routers DHCP Denial of Service Vulnerability

A vulnerability in the DHCP message handler of Cisco IOS XE Software for Cisco cBR-8 Converged Broadband Routers could allow an unauthenticated, remote attacker to cause the supervisor to crash, which could result in a denial of service (DoS) condition.

The vulnerability is due to insufficient error handling when DHCP version 4 (DHCPv4) messages are parsed. An attacker could exploit this vulnerability by sending a malicious DHCPv4 message to or through a WAN interface of an affected device. A successful exploit could allow the attacker to cause a reload of the affected device.

Note: On Cisco cBR-8 Converged Broadband Routers, all of the following are considered WAN interfaces:

10 Gbps Ethernet interfaces
100 Gbps Ethernet interfaces
Port channel interfaces that include multiple 10 and/or 100 Gbps Ethernet interfaces

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-iosxe-dhcp-dos-JSCKX43h [“https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-dhcp-dos-JSCKX43h”]

This advisory is part of the September 24, 2020, release of the Cisco IOS and IOS XE Software Security Advisory Bundled Publication, which includes 25 Cisco Security Advisories that describe 34 vulnerabilities. For a complete list of the advisories and links to them, see Cisco Event Response: September 2020 Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled Publication [“https://sec.cloudapps.cisco.com/security/center/viewErp.x?alertId=ERP-74268”].