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CVE-2021-34737 Detail

Modified

This vulnerability has been modified since it was last analyzed by the NVD. It is awaiting reanalysis which may result in further changes to the information provided.

Description

A vulnerability in the DHCP version 4 (DHCPv4) server feature of Cisco IOS XR Software could allow an unauthenticated, remote attacker to trigger a crash of the dhcpd process, resulting in a denial of service (DoS) condition. This vulnerability exists because certain DHCPv4 messages are improperly validated when they are processed by an affected device. An attacker could exploit this vulnerability by sending a malformed DHCPv4 message to an affected device. A successful exploit could allow the attacker to cause a NULL pointer dereference, resulting in a crash of the dhcpd process. While the dhcpd process is restarting, which may take up to approximately two minutes, DHCPv4 server services are unavailable on the affected device. This could temporarily prevent network access to clients that join the network during that time period. Note: Only the dhcpd process crashes and eventually restarts automatically. The router does not reload.

Severity

CVSS 3.x Severity and Metrics:

NIST: NVD

Base Score: 7.5 HIGH

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

Nist CVSS score does not match with CNA score

CNA: Cisco Systems, Inc.

Base Score: 5.8 MEDIUM

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

NVD Analysts use publicly available information to associate vector strings and CVSS scores. We also display any CVSS information provided within the CVE List from the CNA.

Note: It is possible that the NVD CVSS may not match that of the CNA. The most common reason for this is that publicly available information does not provide sufficient detail or that information simply was not available at the time the CVSS vector string was assigned.

References to Advisories, Solutions, and Tools

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Hyperlink	Resource
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-dhcp-dos-pjPVReLU	Vendor Advisory

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-476	NULL Pointer Dereference	NIST Cisco Systems, Inc.

Known Affected Software Configurations Switch to CPE 2.2

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Change History

3 change records found show changes

Initial Analysis by NIST 9/22/2021 11:10:14 AM

Action	Type	Old Value	New Value
Added	CPE Configuration		Record truncated, showing 500 of 939 characters. View Entire Change Record AND OR cpe:2.3:o:cisco:ios_xr::::::::* versions up to (excluding) 7.3.2 cpe:2.3:o:cisco:ios_xr::::::::* versions from (including) 7.4.0 up to (excluding) 7.4.1 OR cpe:2.3:h:cisco:ncs540-12z20g-sys-a:-:::::::* cpe:2.3:h:cisco:ncs540-12z20g-sys-d:-:::::::* cpe:2.3:h:cisco:ncs540-24z8q2c-m:-:::::::* cpe:2.3:h:cisco:ncs540-24z8q2c-sys:-:::::::* cpe:2.3:h:cisco:ncs540-28z4c-sys-a:-:
Added	CPE Configuration		AND OR cpe:2.3:o:cisco:ios_xr::::::::* versions up to (excluding) 7.3.2 cpe:2.3:o:cisco:ios_xr::::::::* versions from (including) 7.4.0 up to (excluding) 7.4.1 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		Record truncated, showing 500 of 520 characters. View Entire Change Record AND OR cpe:2.3:o:cisco:ios_xr::::::::* versions up to (excluding) 7.3.2 cpe:2.3:o:cisco:ios_xr::::::::* versions from (including) 7.4.0 up to (excluding) 7.4.1 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_
Added	CPE Configuration		AND OR cpe:2.3:o:cisco:ios_xr::::::::* versions up to (excluding) 7.3.2 cpe:2.3:o:cisco:ios_xr::::::::* versions from (including) 7.4.0 up to (excluding) 7.4.1 OR cpe:2.3:h:cisco:ncs_560-4:-:::::::* cpe:2.3:h:cisco:ncs_560-7:-:::::::*
Added	CPE Configuration		Record truncated, showing 500 of 824 characters. View Entire Change Record AND OR cpe:2.3:o:cisco:ios_xr::::::::* versions up to (excluding) 7.3.2 cpe:2.3:o:cisco:ios_xr::::::::* versions from (including) 7.4.0 up to (including) 7.4.1 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_99
Added	CPE Configuration		AND OR cpe:2.3:o:cisco:ios_xr::::::::* versions up to (excluding) 7.3.2 cpe:2.3:o:cisco:ios_xr::::::::* versions from (including) 7.4.0 up to (including) 7.4.1 OR cpe:2.3:h:cisco:ios_xrv_9000:-:::::::*
Added	CVSS V2		NIST (AV:N/AC:L/Au:N/C:N/I:N/A:P)
Added	CVSS V3.1		NIST AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Added	CWE		NIST CWE-476
Changed	Reference Type	https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-dhcp-dos-pjPVReLU No Types Assigned	https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-dhcp-dos-pjPVReLU Vendor Advisory

Quick Info

CVE Dictionary Entry:
CVE-2021-34737
NVD Published Date:
09/09/2021
NVD Last Modified:
11/06/2023
Source:
Cisco Systems, Inc.

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