What is the vulnerability ID?

The vulnerability ID is CVE-2021-34720.

What is the severity of CVE-2021-34720?

The severity of CVE-2021-34720 is high (8.6).

What software is affected by CVE-2021-34720?

Cisco IOS XR Software versions 6.2.3 to 6.3.2 and 6.5.0 to 7.2.2 are affected by CVE-2021-34720.

How can an attacker exploit CVE-2021-34720?

An attacker can exploit CVE-2021-34720 by sending specially crafted packets to the IP SLA responder or TWAMP features of Cisco IOS XR Software.

Is there a fix for CVE-2021-34720?

Yes, Cisco has released software updates to address the vulnerability. Please refer to the Cisco security advisory for more information.

Vulnerability/
CVE-2021-34720

high

8.6

CWE

771

9/9/2021

7/11/2024

CVE-2021-34720: Cisco IOS XR Software IP Service Level Agreements and Two-Way Active Measurement Protocol Denial of Service Vulnerability

First published: Thu Sep 09 2021(Updated: )

A vulnerability in the IP Service Level Agreements (IP SLA) responder and Two-Way Active Measurement Protocol (TWAMP) features of Cisco IOS XR Software could allow an unauthenticated, remote attacker to cause device packet memory to become exhausted or cause the IP SLA process to crash, resulting in a denial of service (DoS) condition. This vulnerability exists because socket creation failures are mishandled during the IP SLA and TWAMP processes. An attacker could exploit this vulnerability by sending specific IP SLA or TWAMP packets to an affected device. A successful exploit could allow the attacker to exhaust the packet memory, which will impact other processes, such as routing protocols, or crash the IP SLA process.

Credit: ykramarz@cisco.com

Affected Software	Affected Version	How to fix
Cisco IOS XR	<6.2.3
Cisco IOS XR	>=6.3.0<6.3.2
Cisco IOS XR	>=6.5.0<7.2.2
Cisco Asr 9000v-v2
Cisco Asr 9001
Cisco Asr 9006
Cisco Asr 9010
Cisco Asr 9901
Cisco Asr 9902
Cisco Asr 9903
Cisco Asr 9904
Cisco Asr 9906
Cisco Asr 9910
Cisco Asr 9912
Cisco Asr 9922
Cisco Ios Xrv
Cisco Ios Xrv 9000
Cisco Ncs 520
Cisco Ncs 540
Cisco Ncs 540 Fronthaul
Cisco Ncs 560-4
Cisco Ncs 560-7
Cisco Ncs 5001
Cisco Ncs 5002
Cisco Ncs 5011
Cisco Ncs 4009
Cisco Ncs 4016
Cisco Ncs 5501
Cisco Ncs 5501-se
Cisco Ncs 5502
Cisco Ncs 5502-se
Cisco Ncs 5508
Cisco Ncs 5516
Cisco Ncs 6000
Cisco Ncs 6008
Cisco Ncs 1001
Cisco Ncs 1002
Cisco Ncs 1004
Cisco 8101-32fh
Cisco 8101-32h
Cisco 8102-64h
Cisco 8201
Cisco 8201-32fh
Cisco 8202
Cisco 8804
Cisco 8808
Cisco 8812
Cisco 8818

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Reference Links

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ipsla-ZA3SRrpP

Frequently Asked Questions

What is the vulnerability ID?
The vulnerability ID is CVE-2021-34720.
What is the severity of CVE-2021-34720?
The severity of CVE-2021-34720 is high (8.6).
What software is affected by CVE-2021-34720?
Cisco IOS XR Software versions 6.2.3 to 6.3.2 and 6.5.0 to 7.2.2 are affected by CVE-2021-34720.
How can an attacker exploit CVE-2021-34720?
An attacker can exploit CVE-2021-34720 by sending specially crafted packets to the IP SLA responder or TWAMP features of Cisco IOS XR Software.
Is there a fix for CVE-2021-34720?
Yes, Cisco has released software updates to address the vulnerability. Please refer to the Cisco security advisory for more information.