Vulnerability-Lookup

BDU:2021-04577 (CVE-2021-34737)

Vulnerability from fstec – Published: 2021-09-20 – Updated: 2021-09-20 – View on bdu.fstec.ru Fixed

Title

Уязвимость службы DHCP-сервера операционной системы Cisco IOS XR, позволяющая нарушителю вызвать сбой процесса dhcpd

Summary

Уязвимость службы DHCP-сервера операционной системы Cisco IOS XR связана с ошибками при обработке DHCPv4 сообщений. Эксплуатация уязвимости может позволить нарушителю, действующему удалённо, вызвать сбой процесса dhcpd

Severity

5.0 (Medium) CVSS 2.0


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

5.8 (Medium) CVSS 3.0


                      
                        CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L

Class

Code vulnerability

Status

Confirmed by the vendor

Exploitation

Data structure manipulation

Incidents

Being clarified

Remediation

Software update

CWE

CWE-476 - Разыменование указателя NULL

Aliases

CVE-2021-34737

References

1 reference

URL
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-…

Impacted products

1 product from 2 vendors

Vendors

Cisco Systems, Inc.

Products

Cisco IOS XR

Versions

до 7.3.2 (Cisco IOS XR), до 7.4.1 (Cisco IOS XR)

Product types

Operating system

Platforms

Cisco Systems, Inc. Cisco IOS XR до 7.3.2 Network Convergence System (NCS) 540 Series Routers, Inc. Cisco IOS XR до 7.4.1 Network Convergence System (NCS) 540 Series Routers, Inc. Cisco IOS XR до 7.3.2 ASR 9000 Series Aggregation Services Routers, Inc. Cisco IOS XR до 7.3.2 IOS XRv 9000 Router, Inc. Cisco IOS XR до 7.3.2 Network Convergence System (NCS) 560 Series Routers, Inc. Cisco IOS XR до 7.3.2 Network Convergence System (NCS) 5000 Series Routers, Inc. Cisco IOS XR до 7.3.2 Network Convergence System (NCS) 5500 Series Routers, Inc. Cisco IOS XR до 7.4.1 ASR 9000 Series Aggregation Services Routers, Inc. Cisco IOS XR до 7.4.1 IOS XRv 9000 Router, Inc. Cisco IOS XR до 7.4.1 Network Convergence System (NCS) 560 Series Routers, Inc. Cisco IOS XR до 7.4.1 Network Convergence System (NCS) 5000 Series Routers, Inc. Cisco IOS XR до 7.4.1 Network Convergence System (NCS) 5500 Series Routers

Mitigations

Использование рекомендаций: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-dhcp-dos-pjPVReLU?vsfCisco20Security20AdvisoryvscatSecurity20IntelligencevstypeRSSvspCisco20IOS20XR20Software20DHCP20Version20420Server20Denial20of20Service20Vulnerabilityvsk1

JSON

To clipboard

{
  "CVSS 2.0": "AV:N/AC:L/Au:N/C:N/I:N/A:P",
  "CVSS 3.0": "AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L",
  "CVSS 4.0": null,
  "remediation_\u0418\u0434\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0440": null,
  "remediation_\u041d\u0430\u0438\u043c\u0435\u043d\u043e\u0432\u0430\u043d\u0438\u0435": null,
  "\u0412\u0435\u043d\u0434\u043e\u0440 \u041f\u041e": "Cisco Systems, Inc.",
  "\u0412\u0435\u0440\u0441\u0438\u044f \u041f\u041e": "\u0434\u043e 7.3.2 (Cisco IOS XR), \u0434\u043e 7.4.1 (Cisco IOS XR)",
  "\u0412\u043e\u0437\u043c\u043e\u0436\u043d\u044b\u0435 \u043c\u0435\u0440\u044b \u043f\u043e \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0438\u044e": "\u0418\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u0435 \u0440\u0435\u043a\u043e\u043c\u0435\u043d\u0434\u0430\u0446\u0438\u0439:\nhttps://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-dhcp-dos-pjPVReLU?vsfCisco20Security20AdvisoryvscatSecurity20IntelligencevstypeRSSvspCisco20IOS20XR20Software20DHCP20Version20420Server20Denial20of20Service20Vulnerabilityvsk1",
  "\u0414\u0430\u0442\u0430 \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0438\u044f": "08.09.2021",
  "\u0414\u0430\u0442\u0430 \u043f\u043e\u0441\u043b\u0435\u0434\u043d\u0435\u0433\u043e \u043e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u044f": "20.09.2021",
  "\u0414\u0430\u0442\u0430 \u043f\u0443\u0431\u043b\u0438\u043a\u0430\u0446\u0438\u0438": "20.09.2021",
  "\u0418\u0434\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0440": "BDU:2021-04577",
  "\u0418\u0434\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0440\u044b \u0434\u0440\u0443\u0433\u0438\u0445 \u0441\u0438\u0441\u0442\u0435\u043c \u043e\u043f\u0438\u0441\u0430\u043d\u0438\u0439 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "CVE-2021-34737",
  "\u0418\u043d\u0444\u043e\u0440\u043c\u0430\u0446\u0438\u044f \u043e\u0431 \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0438\u0438": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0430",
  "\u041a\u043b\u0430\u0441\u0441 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u043a\u043e\u0434\u0430",
  "\u041d\u0430\u0437\u0432\u0430\u043d\u0438\u0435 \u041f\u041e": "Cisco IOS XR",
  "\u041d\u0430\u0438\u043c\u0435\u043d\u043e\u0432\u0430\u043d\u0438\u0435 \u041e\u0421 \u0438 \u0442\u0438\u043f \u0430\u043f\u043f\u0430\u0440\u0430\u0442\u043d\u043e\u0439 \u043f\u043b\u0430\u0442\u0444\u043e\u0440\u043c\u044b": "Cisco Systems, Inc. Cisco IOS XR \u0434\u043e 7.3.2 Network Convergence System (NCS) 540 Series Routers, Cisco Systems, Inc. Cisco IOS XR \u0434\u043e 7.4.1 Network Convergence System (NCS) 540 Series Routers, Cisco Systems, Inc. Cisco IOS XR \u0434\u043e 7.3.2 ASR 9000 Series Aggregation Services Routers, Cisco Systems, Inc. Cisco IOS XR \u0434\u043e 7.3.2 IOS XRv 9000 Router, Cisco Systems, Inc. Cisco IOS XR \u0434\u043e 7.3.2 Network Convergence System (NCS) 560 Series Routers, Cisco Systems, Inc. Cisco IOS XR \u0434\u043e 7.3.2 Network Convergence System (NCS) 5000 Series Routers, Cisco Systems, Inc. Cisco IOS XR \u0434\u043e 7.3.2 Network Convergence System (NCS) 5500 Series Routers, Cisco Systems, Inc. Cisco IOS XR \u0434\u043e 7.4.1 ASR 9000 Series Aggregation Services Routers, Cisco Systems, Inc. Cisco IOS XR \u0434\u043e 7.4.1 IOS XRv 9000 Router, Cisco Systems, Inc. Cisco IOS XR \u0434\u043e 7.4.1 Network Convergence System (NCS) 560 Series Routers, Cisco Systems, Inc. Cisco IOS XR \u0434\u043e 7.4.1 Network Convergence System (NCS) 5000 Series Routers, Cisco Systems, Inc. Cisco IOS XR \u0434\u043e 7.4.1 Network Convergence System (NCS) 5500 Series Routers",
  "\u041d\u0430\u0438\u043c\u0435\u043d\u043e\u0432\u0430\u043d\u0438\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0441\u043b\u0443\u0436\u0431\u044b DHCP-\u0441\u0435\u0440\u0432\u0435\u0440\u0430 \u043e\u043f\u0435\u0440\u0430\u0446\u0438\u043e\u043d\u043d\u043e\u0439 \u0441\u0438\u0441\u0442\u0435\u043c\u044b Cisco IOS XR, \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u043d\u0430\u0440\u0443\u0448\u0438\u0442\u0435\u043b\u044e \u0432\u044b\u0437\u0432\u0430\u0442\u044c \u0441\u0431\u043e\u0439 \u043f\u0440\u043e\u0446\u0435\u0441\u0441\u0430 dhcpd",
  "\u041d\u0430\u043b\u0438\u0447\u0438\u0435 \u044d\u043a\u0441\u043f\u043b\u043e\u0439\u0442\u0430": "\u0414\u0430\u043d\u043d\u044b\u0435 \u0443\u0442\u043e\u0447\u043d\u044f\u044e\u0442\u0441\u044f",
  "\u041e\u043f\u0438\u0441\u0430\u043d\u0438\u0435 \u043e\u0448\u0438\u0431\u043a\u0438 CWE": "\u0420\u0430\u0437\u044b\u043c\u0435\u043d\u043e\u0432\u0430\u043d\u0438\u0435 \u0443\u043a\u0430\u0437\u0430\u0442\u0435\u043b\u044f NULL (CWE-476)",
  "\u041e\u043f\u0438\u0441\u0430\u043d\u0438\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0441\u043b\u0443\u0436\u0431\u044b DHCP-\u0441\u0435\u0440\u0432\u0435\u0440\u0430 \u043e\u043f\u0435\u0440\u0430\u0446\u0438\u043e\u043d\u043d\u043e\u0439 \u0441\u0438\u0441\u0442\u0435\u043c\u044b Cisco IOS XR \u0441\u0432\u044f\u0437\u0430\u043d\u0430 \u0441 \u043e\u0448\u0438\u0431\u043a\u0430\u043c\u0438 \u043f\u0440\u0438 \u043e\u0431\u0440\u0430\u0431\u043e\u0442\u043a\u0435 DHCPv4 \u0441\u043e\u043e\u0431\u0449\u0435\u043d\u0438\u0439. \u042d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0430\u0446\u0438\u044f \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 \u043c\u043e\u0436\u0435\u0442 \u043f\u043e\u0437\u0432\u043e\u043b\u0438\u0442\u044c \u043d\u0430\u0440\u0443\u0448\u0438\u0442\u0435\u043b\u044e, \u0434\u0435\u0439\u0441\u0442\u0432\u0443\u044e\u0449\u0435\u043c\u0443 \u0443\u0434\u0430\u043b\u0451\u043d\u043d\u043e, \u0432\u044b\u0437\u0432\u0430\u0442\u044c \u0441\u0431\u043e\u0439 \u043f\u0440\u043e\u0446\u0435\u0441\u0441\u0430 dhcpd",
  "\u041f\u043e\u0441\u043b\u0435\u0434\u0441\u0442\u0432\u0438\u044f \u044d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0430\u0446\u0438\u0438 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": null,
  "\u041f\u0440\u043e\u0447\u0430\u044f \u0438\u043d\u0444\u043e\u0440\u043c\u0430\u0446\u0438\u044f": null,
  "\u0421\u0432\u044f\u0437\u044c \u0441 \u0438\u043d\u0446\u0438\u0434\u0435\u043d\u0442\u0430\u043c\u0438 \u0418\u0411": "\u0414\u0430\u043d\u043d\u044b\u0435 \u0443\u0442\u043e\u0447\u043d\u044f\u044e\u0442\u0441\u044f",
  "\u0421\u043e\u0441\u0442\u043e\u044f\u043d\u0438\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u041e\u043f\u0443\u0431\u043b\u0438\u043a\u043e\u0432\u0430\u043d\u0430",
  "\u0421\u043f\u043e\u0441\u043e\u0431 \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0438\u044f": "\u041e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u0435 \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u043d\u043e\u0433\u043e \u043e\u0431\u0435\u0441\u043f\u0435\u0447\u0435\u043d\u0438\u044f",
  "\u0421\u043f\u043e\u0441\u043e\u0431 \u044d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0430\u0446\u0438\u0438": "\u041c\u0430\u043d\u0438\u043f\u0443\u043b\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u0435 \u0441\u0442\u0440\u0443\u043a\u0442\u0443\u0440\u0430\u043c\u0438 \u0434\u0430\u043d\u043d\u044b\u0445",
  "\u0421\u0441\u044b\u043b\u043a\u0438 \u043d\u0430 \u0438\u0441\u0442\u043e\u0447\u043d\u0438\u043a\u0438": "https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-dhcp-dos-pjPVReLU?vsfCisco20Security20AdvisoryvscatSecurity20IntelligencevstypeRSSvspCisco20IOS20XR20Software20DHCP20Version20420Server20Denial20of20Service20Vulnerabilityvsk1",
  "\u0421\u0442\u0430\u0442\u0443\u0441 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u041f\u043e\u0434\u0442\u0432\u0435\u0440\u0436\u0434\u0435\u043d\u0430 \u043f\u0440\u043e\u0438\u0437\u0432\u043e\u0434\u0438\u0442\u0435\u043b\u0435\u043c",
  "\u0422\u0438\u043f \u041f\u041e": "\u041e\u043f\u0435\u0440\u0430\u0446\u0438\u043e\u043d\u043d\u0430\u044f \u0441\u0438\u0441\u0442\u0435\u043c\u0430",
  "\u0422\u0438\u043f \u043e\u0448\u0438\u0431\u043a\u0438 CWE": "CWE-476",
  "\u0423\u0440\u043e\u0432\u0435\u043d\u044c \u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u0421\u0440\u0435\u0434\u043d\u0438\u0439 \u0443\u0440\u043e\u0432\u0435\u043d\u044c \u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 (\u0431\u0430\u0437\u043e\u0432\u0430\u044f \u043e\u0446\u0435\u043d\u043a\u0430 CVSS 2.0 \u0441\u043e\u0441\u0442\u0430\u0432\u043b\u044f\u0435\u0442 5)\n\u0421\u0440\u0435\u0434\u043d\u0438\u0439 \u0443\u0440\u043e\u0432\u0435\u043d\u044c \u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 (\u0431\u0430\u0437\u043e\u0432\u0430\u044f \u043e\u0446\u0435\u043d\u043a\u0430 CVSS 3.0 \u0441\u043e\u0441\u0442\u0430\u0432\u043b\u044f\u0435\u0442 5,8)"
}

CVE-2021-34737 (GCVE-0-2021-34737)

Vulnerability from cvelistv5 – Published: 2021-09-09 05:01 – Updated: 2024-11-07 22:00

Title

Cisco IOS XR Software DHCP Version 4 Server Denial of Service Vulnerability

Summary

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

5.8 (Medium)


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

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2024-11-07 21:54 UTC

CWE

CWE-476

Assigner

cisco mitre root

References

1 reference

URL	Tags
https://tools.cisco.com/security/center/content/C…	vendor-advisoryx_refsource_CISCO

Impacted products

1 product

Vendor	Product	Version
Cisco	Cisco IOS XR Software	Affected: n/a

Date Public

2021-09-08 00:00

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2024-08-04T00:19:48.091Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "name": "20210908 Cisco IOS XR Software DHCP Version 4 Server Denial of Service Vulnerability",
            "tags": [
              "vendor-advisory",
              "x_refsource_CISCO",
              "x_transferred"
            ],
            "url": "https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-dhcp-dos-pjPVReLU"
          }
        ],
        "title": "CVE Program Container"
      },
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2021-34737",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2024-11-07T21:54:21.168817Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2024-11-07T22:00:23.958Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "Cisco IOS XR Software",
          "vendor": "Cisco",
          "versions": [
            {
              "status": "affected",
              "version": "n/a"
            }
          ]
        }
      ],
      "datePublic": "2021-09-08T00:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "value": "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."
        }
      ],
      "exploits": [
        {
          "lang": "en",
          "value": "The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "LOW",
            "baseScore": 5.8,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "CHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-476",
              "description": "CWE-476",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2021-09-09T05:01:30.000Z",
        "orgId": "d1c1063e-7a18-46af-9102-31f8928bc633",
        "shortName": "cisco"
      },
      "references": [
        {
          "name": "20210908 Cisco IOS XR Software DHCP Version 4 Server Denial of Service Vulnerability",
          "tags": [
            "vendor-advisory",
            "x_refsource_CISCO"
          ],
          "url": "https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-dhcp-dos-pjPVReLU"
        }
      ],
      "source": {
        "advisory": "cisco-sa-iosxr-dhcp-dos-pjPVReLU",
        "defect": [
          [
            "CSCvw95930"
          ]
        ],
        "discovery": "INTERNAL"
      },
      "title": "Cisco IOS XR Software DHCP Version 4 Server Denial of Service Vulnerability",
      "x_legacyV4Record": {
        "CVE_data_meta": {
          "ASSIGNER": "psirt@cisco.com",
          "DATE_PUBLIC": "2021-09-08T16:00:00",
          "ID": "CVE-2021-34737",
          "STATE": "PUBLIC",
          "TITLE": "Cisco IOS XR Software DHCP Version 4 Server Denial of Service Vulnerability"
        },
        "affects": {
          "vendor": {
            "vendor_data": [
              {
                "product": {
                  "product_data": [
                    {
                      "product_name": "Cisco IOS XR Software",
                      "version": {
                        "version_data": [
                          {
                            "version_value": "n/a"
                          }
                        ]
                      }
                    }
                  ]
                },
                "vendor_name": "Cisco"
              }
            ]
          }
        },
        "data_format": "MITRE",
        "data_type": "CVE",
        "data_version": "4.0",
        "description": {
          "description_data": [
            {
              "lang": "eng",
              "value": "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."
            }
          ]
        },
        "exploit": [
          {
            "lang": "en",
            "value": "The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory."
          }
        ],
        "impact": {
          "cvss": {
            "baseScore": "5.8",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L",
            "version": "3.0"
          }
        },
        "problemtype": {
          "problemtype_data": [
            {
              "description": [
                {
                  "lang": "eng",
                  "value": "CWE-476"
                }
              ]
            }
          ]
        },
        "references": {
          "reference_data": [
            {
              "name": "20210908 Cisco IOS XR Software DHCP Version 4 Server Denial of Service Vulnerability",
              "refsource": "CISCO",
              "url": "https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-dhcp-dos-pjPVReLU"
            }
          ]
        },
        "source": {
          "advisory": "cisco-sa-iosxr-dhcp-dos-pjPVReLU",
          "defect": [
            [
              "CSCvw95930"
            ]
          ],
          "discovery": "INTERNAL"
        }
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "d1c1063e-7a18-46af-9102-31f8928bc633",
    "assignerShortName": "cisco",
    "cveId": "CVE-2021-34737",
    "datePublished": "2021-09-09T05:01:30.516Z",
    "dateReserved": "2021-06-15T00:00:00.000Z",
    "dateUpdated": "2024-11-07T22:00:23.958Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.