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CiscoCVE-2021-34737

HistorySep 09, 2021 - 5:15 a.m.

CVE-2021-34737

2021-09-0905:15:11

CWE-476

cisco

web.nvd.nist.gov

vulnerability

dhcpv4

cisco ios xr software

denial of service

dos

nvd

cve-2021-34737

CVSS2

Attack Vector

NETWORK

Attack Complexity

LOW

Authentication

NONE

Confidentiality Impact

NONE

Integrity Impact

NONE

Availability Impact

PARTIAL

AV:N/AC:L/Au:N/C:N/I:N/A:P

CVSS3

7.5

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

NONE

Integrity Impact

NONE

Availability Impact

HIGH

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

EPSS

0.002

Percentile

51.9%

JSON

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.

Affected configurations

Nvd

Node

ciscoios_xrRange<7.3.2

ciscoios_xrRange7.4.0–7.4.1

AND

ciscoasr_9000v-v2Match-

ciscoasr_9001Match-

ciscoasr_9006Match-

ciscoasr_9010Match-

ciscoasr_9901Match-

ciscoasr_9902Match-

ciscoasr_9903Match-

ciscoasr_9904Match-

ciscoasr_9906Match-

ciscoasr_9910Match-

ciscoasr_9912Match-

ciscoasr_9922Match-

Node

ciscoios_xrRange<7.3.2

ciscoios_xrRange7.4.0–7.4.1

AND

ciscoios_xrv_9000Match-

Node

cisconcs540-12z20g-sys-aMatch-

cisconcs540-12z20g-sys-dMatch-

cisconcs540-24z8q2c-mMatch-

cisconcs540-24z8q2c-sysMatch-

cisconcs540-28z4c-sys-aMatch-

cisconcs540-28z4c-sys-dMatch-

cisconcs540-acc-sysMatch-

cisconcs540x-12z16g-sys-aMatch-

cisconcs540x-12z16g-sys-dMatch-

cisconcs540x-16z4g8q2c-aMatch-

cisconcs540x-16z4g8q2c-dMatch-

cisconcs540x-acc-sysMatch-

AND

ciscoios_xrRange<7.3.2

ciscoios_xrRange7.4.0–7.4.1

Node

cisconcs_5001Match-

cisconcs_5002Match-

cisconcs_5011Match-

AND

ciscoios_xrRange<7.3.2

ciscoios_xrRange7.4.0–7.4.1

Node

cisconcs_560-4Match-

cisconcs_560-7Match-

AND

ciscoios_xrRange<7.3.2

ciscoios_xrRange7.4.0–7.4.1

Node

cisconcs_5501Match-

cisconcs_5501-seMatch-

cisconcs_5502Match-

cisconcs_5502-seMatch-

cisconcs_5508Match-

cisconcs_5516Match-

AND

ciscoios_xrRange<7.3.2

ciscoios_xrRange7.4.0–7.4.1

VendorProductVersionCPE
ciscoios_xr*cpe:2.3:o:cisco:ios_xr:*:*:*:*:*:*:*:*
ciscoasr_9000v-v2-cpe:2.3:h:cisco:asr_9000v-v2:-:*:*:*:*:*:*:*
ciscoasr_9001-cpe:2.3:h:cisco:asr_9001:-:*:*:*:*:*:*:*
ciscoasr_9006-cpe:2.3:h:cisco:asr_9006:-:*:*:*:*:*:*:*
ciscoasr_9010-cpe:2.3:h:cisco:asr_9010:-:*:*:*:*:*:*:*
ciscoasr_9901-cpe:2.3:h:cisco:asr_9901:-:*:*:*:*:*:*:*
ciscoasr_9902-cpe:2.3:h:cisco:asr_9902:-:*:*:*:*:*:*:*
ciscoasr_9903-cpe:2.3:h:cisco:asr_9903:-:*:*:*:*:*:*:*
ciscoasr_9904-cpe:2.3:h:cisco:asr_9904:-:*:*:*:*:*:*:*
ciscoasr_9906-cpe:2.3:h:cisco:asr_9906:-:*:*:*:*:*:*:*

Vendor	Product	Version	CPE
cisco	ios_xr	*	cpe:2.3:o:cisco:ios_xr::::::::
cisco	asr_9000v-v2	-	cpe:2.3:h:cisco:asr_9000v-v2:-:::::::*
cisco	asr_9001	-	cpe:2.3:h:cisco:asr_9001:-:::::::*
cisco	asr_9006	-	cpe:2.3:h:cisco:asr_9006:-:::::::*
cisco	asr_9010	-	cpe:2.3:h:cisco:asr_9010:-:::::::*
cisco	asr_9901	-	cpe:2.3:h:cisco:asr_9901:-:::::::*
cisco	asr_9902	-	cpe:2.3:h:cisco:asr_9902:-:::::::*
cisco	asr_9903	-	cpe:2.3:h:cisco:asr_9903:-:::::::*
cisco	asr_9904	-	cpe:2.3:h:cisco:asr_9904:-:::::::*
cisco	asr_9906	-	cpe:2.3:h:cisco:asr_9906:-:::::::*

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1-10 of 371

CNA Affected

[
  {
    "product": "Cisco IOS XR Software",
    "vendor": "Cisco",
    "versions": [
      {
        "status": "affected",
        "version": "n/a"
      }
    ]
  }
]

References

tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-dhcp-dos-pjPVReLU

CVSS2

Attack Vector

NETWORK

Attack Complexity

LOW

Authentication

NONE

Confidentiality Impact

NONE

Integrity Impact

NONE

Availability Impact

PARTIAL

AV:N/AC:L/Au:N/C:N/I:N/A:P

CVSS3

7.5

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

NONE

Integrity Impact

NONE

Availability Impact

HIGH

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

EPSS

0.002

Percentile

51.9%

JSON

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