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Cisco IOS XR Software Cisco Discovery Protocol Denial of Service Vulnerability

cisco-sa-xr-cdp-wnALzvT2 · Medium · Published · Updated

A vulnerability in the Cisco Discovery Protocol implementation for Cisco IOS XR Software could allow an unauthenticated, adjacent attacker to cause the Cisco Discovery Protocol process to reload on an affected device. This vulnerability is due to a heap buffer overflow in certain 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 heap overflow, which could cause the Cisco Discovery Protocol process to reload on the device. The bytes that can be written in the buffer overflow are restricted, which limits remote code execution. 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-xr-cdp-wnALzvT2 This advisory is part of the September 2022 release of the Cisco IOS XR Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2022 Semiannual Cisco IOS XR Software Security Advisory Bundled Publication.

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, use the no cdp command in global configuration mode, as shown in the following example:

RP/0/RP0/CPU0:iosxr#conf t
Mon Sep 23 17:58:08.556 UTC RP/0/RP0/CPU0:iosxr(config)#no cdp RP/0/RP0/CPU0:iosxr(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, use the no cdp command in interface configuration mode, as shown in the following example:

RP/0/RP0/CPU0:iosxr#conf t
Mon Sep 23 18:00:08.622 UTC RP/0/RP0/CPU0:iosxr(config)#interface GigabitEthernet0/0/0/0 RP/0/RP0/CPU0:iosxr(config-if)#no cdp RP/0/RP0/CPU0:iosxr(config-if)#end Uncommitted changes found, commit them before exiting(yes/no/cancel)? [cancel]:yes

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.

CVEsCVE-2022-20846
Cisco Bug IDsCSCwb23263
CVSS ScoreBase 4.3
Base 4.3 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:X/RL:X/RC:X
Product Names From Source
Cisco IOS XR Software

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