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Cisco IOS XR Software Cisco Discovery Protocol Format String Vulnerability

cisco-sa-20200205-iosxr-cdp-rce · High · Published · Updated

A vulnerability in the Cisco Discovery Protocol implementation for Cisco IOS XR Software could allow an unauthenticated, adjacent attacker to execute arbitrary code or cause a reload on an affected device. The vulnerability is due to improper validation of string input from certain fields in Cisco Discovery Protocol messages. An attacker could exploit this vulnerability by sending a malicious Cisco Discovery Protocol packet to an affected device. A successful exploit could allow the attacker to cause a stack overflow, which could allow the attacker to execute arbitrary code with administrative privileges on an affected device. Note: Cisco Discovery Protocol is a Layer 2 protocol. To exploit this vulnerability, an attacker must be in the same broadcast domain as the affected device (Layer 2 adjacent). 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-20200205-iosxr-cdp-rce

Cisco advisory ·CSAF JSON

Workarounds

There are no workarounds that address this vulnerability.

However, customers who do not use the Cisco Discovery Protocol feature can disable it either globally to fully close the attack vector or on individual interfaces to reduce the attack surface.
Disable Cisco Discovery Protocol Globally
To disable Cisco Discovery Protocol globally on devices that are running Cisco IOS XR Software, administrators can use the no cdp command in global configuration mode, as shown in the following example:

RP/0/RP0/CPU0:ios#conf t
Mon Dec 2 17:58:08.556 UTC RP/0/RP0/CPU0:ios(config)#no cdp RP/0/RP0/CPU0:ios(config)#exit
Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]:yes
Disable Cisco Discovery Protocol on an Interface
To disable Cisco Discovery Protocol on an interface on devices that are running Cisco IOS XR Software, administrators can use the no cdp command in interface configuration mode, as shown in the following example:

RP/0/RP0/CPU0:ios#conf t
Mon Dec 2 18:00:08.622 UTC RP/0/RP0/CPU0:ios(config)#interface GigabitEthernet0/0/0/0 RP/0/RP0/CPU0:ios(config-if)#no cdp RP/0/RP0/CPU0:ios(config-if)#end Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]:yes

CVEsCVE-2020-3118
Cisco Bug IDsCSCvr09190
CVSS ScoreBase 8.8
Base 8.8 CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:X/RL:X/RC:X
Product Names From Source
Cisco IOS XR Software

CSAF Product Statuses

Product Status Source CVE Rows
Cisco IOS XR Software known_affected cisco_csaf CVE-2020-3118 1

Related Products

Product CVE Evidence
Cisco IOS XR Software CVE-2020-3118 Cisco OpenVuln
Cisco IOS CVE-2020-3118 Cisco OpenVuln
Cisco IOS Software CVE-2020-3118 Cisco OpenVuln