NVD

CVE-2021-34720 Detail

Modified After Enrichment

This CVE record has been updated after NVD enrichment efforts were completed. Enrichment data supplied by the NVD may require amendment due to these changes.

Description

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.

Metrics

NVD enrichment efforts reference publicly available information to associate vector strings. CVSS information contributed by other sources is also displayed.

CVSS 4.0 Severity and Vector Strings:

NIST: NVD

N/A

NVD assessment not yet provided.

CVSS 3.x Severity and Vector Strings:

CNA: Cisco Systems, Inc.

Base Score: 8.6 HIGH

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

CVSS 2.0 Severity and Vector Strings:

National Institute of Standards and Technology

NIST: NVD

Base Score: 4.3 MEDIUM

Vector: (AV:N/AC:M/Au:N/C:N/I:N/A:P)

References to Advisories, Solutions, and Tools

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URL	Source(s)	Tag(s)
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ipsla-ZA3SRrpP	CVE, Cisco Systems, Inc.	Vendor Advisory

Weakness Enumeration

CWE-ID	CWE Name	Source
NVD-CWE-Other	Other	NIST
CWE-771	Missing Reference to Active Allocated Resource	Cisco Systems, Inc.

Known Affected Software Configurations Switch to CPE 2.2

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Denotes Vulnerable Software
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Change History

7 change records found show changes

Initial Analysis by NIST 9/22/2021 10:56:21 AM

Action	Type	Old Value	New Value
Added	CVSS V3.1		NIST AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Added	CVSS V2		NIST (AV:N/AC:M/Au:N/C:N/I:N/A:P)
Added	CWE		NIST CWE-400
Added	CPE Configuration		AND OR cpe:2.3:o:cisco:ios_xr::::::::* versions up to (excluding) 6.2.3 cpe:2.3:o:cisco:ios_xr::::::::* versions from (including) 6.3.0 up to (excluding) 6.3.2 cpe:2.3:o:cisco:ios_xr::::::::* versions from (including) 6.5.0 up to (excluding) 7.2.2 OR cpe:2.3:h:cisco:8101-32fh:-:::::::* cpe:2.3:h:cisco:8101-32h:-:::::::* cpe:2.3:h:cisco:8102-64h:-:::::::* cpe:2.3:h:cisco:8201:-:::::::* cpe:2.3:h:cisco:8201-32fh:-:::::::* cpe:2.3:h:cisco:8202:-:::::::* cpe:2.3:h:cisco:8804:-:::::::* cpe:2.3:h:cisco:8808:-:::::::* cpe:2.3:h:cisco:8812:-:::::::* cpe:2.3:h:cisco:8818:-:::::::*
Added	CPE Configuration		AND OR cpe:2.3:o:cisco:ios_xr::::::::* versions up to (excluding) 6.2.3 cpe:2.3:o:cisco:ios_xr::::::::* versions from (including) 6.3.0 up to (excluding) 6.3.2 cpe:2.3:o:cisco:ios_xr::::::::* versions from (including) 6.5.0 up to (excluding) 7.2.2 OR cpe:2.3:h:cisco:asr_9000v-v2:-:::::::* cpe:2.3:h:cisco:asr_9001:-:::::::* cpe:2.3:h:cisco:asr_9006:-:::::::* cpe:2.3:h:cisco:asr_9010:-:::::::* cpe:2.3:h:cisco:asr_9901:-:::::::* cpe:2.3:h:cisco:asr_9902:-:::::::* cpe:2.3:h:cisco:asr_9903:-:::::::* cpe:2.3:h:cisco:asr_9904:-:::::::* cpe:2.3:h:cisco:asr_9906:-:::::::* cpe:2.3:h:cisco:asr_9910:-:::::::* cpe:2.3:h:cisco:asr_9912:-:::::::* cpe:2.3:h:cisco:asr_9922:-:::::::*
Added	CPE Configuration		AND OR cpe:2.3:o:cisco:ios_xr::::::::* versions up to (excluding) 6.2.3 cpe:2.3:o:cisco:ios_xr::::::::* versions from (including) 6.3.0 up to (excluding) 6.3.2 cpe:2.3:o:cisco:ios_xr::::::::* versions from (including) 6.5.0 up to (excluding) 7.2.2 OR cpe:2.3:h:cisco:ios_xrv:-:::::::* cpe:2.3:h:cisco:ios_xrv_9000:-:::::::*
Added	CPE Configuration		AND OR cpe:2.3:o:cisco:ios_xr::::::::* versions up to (excluding) 6.2.3 cpe:2.3:o:cisco:ios_xr::::::::* versions from (including) 6.3.0 up to (excluding) 6.3.2 cpe:2.3:o:cisco:ios_xr::::::::* versions from (including) 6.5.0 up to (excluding) 7.2.2 OR cpe:2.3:h:cisco:ncs_1001:-:::::::* cpe:2.3:h:cisco:ncs_1002:-:::::::* cpe:2.3:h:cisco:ncs_1004:-:::::::*
Added	CPE Configuration		AND OR cpe:2.3:o:cisco:ios_xr::::::::* versions up to (excluding) 6.2.3 cpe:2.3:o:cisco:ios_xr::::::::* versions from (including) 6.3.0 up to (excluding) 6.3.2 cpe:2.3:o:cisco:ios_xr::::::::* versions from (including) 6.5.0 up to (excluding) 7.2.2 OR cpe:2.3:h:cisco:ncs_4009:-:::::::* cpe:2.3:h:cisco:ncs_4016:-:::::::*
Added	CPE Configuration		AND OR cpe:2.3:o:cisco:ios_xr::::::::* versions up to (excluding) 6.2.3 cpe:2.3:o:cisco:ios_xr::::::::* versions from (including) 6.3.0 up to (excluding) 6.3.2 cpe:2.3:o:cisco:ios_xr::::::::* versions from (including) 6.5.0 up to (excluding) 7.2.2 OR cpe:2.3:h:cisco:ncs_5001:-:::::::* cpe:2.3:h:cisco:ncs_5002:-:::::::* cpe:2.3:h:cisco:ncs_5011:-:::::::*
Added	CPE Configuration		AND OR cpe:2.3:o:cisco:ios_xr::::::::* versions up to (excluding) 6.2.3 cpe:2.3:o:cisco:ios_xr::::::::* versions from (including) 6.3.0 up to (excluding) 6.3.2 cpe:2.3:o:cisco:ios_xr::::::::* versions from (including) 6.5.0 up to (excluding) 7.2.2 OR cpe:2.3:h:cisco:ncs_520:-:::::::* cpe:2.3:h:cisco:ncs_540:-:::::::* cpe:2.3:h:cisco:ncs_540_fronthaul:-:::::::* cpe:2.3:h:cisco:ncs_560-4:-:::::::* cpe:2.3:h:cisco:ncs_560-7:-:::::::*
Added	CPE Configuration		AND OR cpe:2.3:o:cisco:ios_xr::::::::* versions up to (excluding) 6.2.3 cpe:2.3:o:cisco:ios_xr::::::::* versions from (including) 6.3.0 up to (excluding) 6.3.2 cpe:2.3:o:cisco:ios_xr::::::::* versions from (including) 6.5.0 up to (excluding) 7.2.2 OR cpe:2.3:h:cisco:ncs_5501:-:::::::* cpe:2.3:h:cisco:ncs_5501-se:-:::::::* cpe:2.3:h:cisco:ncs_5502:-:::::::* cpe:2.3:h:cisco:ncs_5502-se:-:::::::* cpe:2.3:h:cisco:ncs_5508:-:::::::* cpe:2.3:h:cisco:ncs_5516:-:::::::*
Added	CPE Configuration		AND OR cpe:2.3:o:cisco:ios_xr::::::::* versions up to (excluding) 6.2.3 cpe:2.3:o:cisco:ios_xr::::::::* versions from (including) 6.3.0 up to (excluding) 6.3.2 cpe:2.3:o:cisco:ios_xr::::::::* versions from (including) 6.5.0 up to (excluding) 7.2.2 OR cpe:2.3:h:cisco:ncs_6000:-:::::::* cpe:2.3:h:cisco:ncs_6008:-:::::::*
Changed	Reference Type	https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ipsla-ZA3SRrpP No Types Assigned	https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ipsla-ZA3SRrpP Vendor Advisory

Quick Info

CVE Dictionary Entry:
CVE-2021-34720
NVD Published Date:
09/09/2021
NVD Last Modified:
06/16/2026
Source:
Cisco Systems, Inc.

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Information Technology Laboratory

National Vulnerability Database

National Vulnerability Database

CVE-2021-34720 Detail

Description

Metrics

References to Advisories, Solutions, and Tools

Weakness Enumeration

Known Affected Software Configurations Switch to CPE 2.2

CPEs loading, please wait.

Change History

CVE Modified by CISA-ADP 6/16/2026 11:56:25 PM

CVE Modified by Cisco Systems, Inc. 6/16/2026 11:56:25 PM

CVE Modified by CVE 11/21/2024 1:11:02 AM

CVE Modified by Cisco Systems, Inc. 5/14/2024 5:14:56 AM

CVE Modified by Cisco Systems, Inc. 11/06/2023 10:36:11 PM

Reanalysis by NIST 10/25/2022 2:04:49 PM

Initial Analysis by NIST 9/22/2021 10:56:21 AM

Quick Info