CVE-2021-34737
CVSS V2 Medium 5
CVSS V3 High 7.5
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.
Overview
- CVE ID
- CVE-2021-34737
- Assigner
- ykramarz@cisco.com
- Vulnerability Status
- Analyzed
- Published Version
- 2021-09-09T05:15:11
- Last Modified Date
- 2021-09-22T15:10:13
Weakness Enumerations
CPE Configuration (Product)
| CPE | Vulnerable | Operator | Version Start | Version End |
|---|---|---|---|---|
| AND | ||||
| cpe:2.3:o:cisco:ios_xr:*:*:*:*:*:*:*:* | 1 | OR | 7.3.2 | |
| cpe:2.3:o:cisco:ios_xr:*:*:*:*:*:*:*:* | 1 | OR | 7.4.0 | 7.4.1 |
| cpe:2.3:h:cisco:asr_9000v-v2:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:asr_9001:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:asr_9006:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:asr_9010:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:asr_9901:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:asr_9902:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:asr_9903:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:asr_9904:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:asr_9906:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:asr_9910:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:asr_9912:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:asr_9922:-:*:*:*:*:*:*:* | 0 | OR | ||
| AND | ||||
| cpe:2.3:o:cisco:ios_xr:*:*:*:*:*:*:*:* | 1 | OR | 7.3.2 | |
| cpe:2.3:o:cisco:ios_xr:*:*:*:*:*:*:*:* | 1 | OR | 7.4.0 | 7.4.1 |
| cpe:2.3:h:cisco:ios_xrv_9000:-:*:*:*:*:*:*:* | 0 | OR | ||
| AND | ||||
| cpe:2.3:o:cisco:ios_xr:*:*:*:*:*:*:*:* | 1 | OR | 7.3.2 | |
| cpe:2.3:o:cisco:ios_xr:*:*:*:*:*:*:*:* | 1 | OR | 7.4.0 | 7.4.1 |
| cpe:2.3:h:cisco:ncs540-12z20g-sys-a:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:ncs540-12z20g-sys-d:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:ncs540-24z8q2c-m:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:ncs540-24z8q2c-sys:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:ncs540-28z4c-sys-a:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:ncs540-28z4c-sys-d:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:ncs540-acc-sys:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:ncs540x-12z16g-sys-a:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:ncs540x-12z16g-sys-d:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:ncs540x-16z4g8q2c-a:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:ncs540x-16z4g8q2c-d:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:ncs540x-acc-sys:-:*:*:*:*:*:*:* | 0 | OR | ||
| AND | ||||
| cpe:2.3:o:cisco:ios_xr:*:*:*:*:*:*:*:* | 1 | OR | 7.3.2 | |
| cpe:2.3:o:cisco:ios_xr:*:*:*:*:*:*:*:* | 1 | OR | 7.4.0 | 7.4.1 |
| cpe:2.3:h:cisco:ncs_5001:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:ncs_5002:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:ncs_5011:-:*:*:*:*:*:*:* | 0 | OR | ||
| AND | ||||
| cpe:2.3:o:cisco:ios_xr:*:*:*:*:*:*:*:* | 1 | OR | 7.3.2 | |
| cpe:2.3:o:cisco:ios_xr:*:*:*:*:*:*:*:* | 1 | OR | 7.4.0 | 7.4.1 |
| cpe:2.3:h:cisco:ncs_560-4:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:ncs_560-7:-:*:*:*:*:*:*:* | 0 | OR | ||
| AND | ||||
| cpe:2.3:o:cisco:ios_xr:*:*:*:*:*:*:*:* | 1 | OR | 7.3.2 | |
| cpe:2.3:o:cisco:ios_xr:*:*:*:*:*:*:*:* | 1 | OR | 7.4.0 | 7.4.1 |
| cpe:2.3:h:cisco:ncs_5501:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:ncs_5501-se:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:ncs_5502:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:ncs_5502-se:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:ncs_5508:-:*:*:*:*:*:*:* | 0 | OR | ||
| cpe:2.3:h:cisco:ncs_5516:-:*:*:*:*:*:*:* | 0 | OR |
CVSS Version 2
- Version
- 2.0
- Vector String
- AV:N/AC:L/Au:N/C:N/I:N/A:P
- Access Vector
- NETWORK
- Access Compatibility
- LOW
- Authentication
- NONE
- Confidentiality Impact
- NONE
- Integrity Impact
- NONE
- Availability Impact
- PARTIAL
- Base Score
- 5
- Severity
- MEDIUM
- Exploitability Score
- 10
- Impact Score
- 2.9
CVSS Version 3
- Version
- 3.1
- Vector String
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Attack Vector
- NETWORK
- Attack Compatibility
- LOW
- Privileges Required
- NONE
- User Interaction
- NONE
- Scope
- UNCHANGED
- Confidentiality Impact
- NONE
- Availability Impact
- HIGH
- Base Score
- 7.5
- Base Severity
- HIGH
- Exploitability Score
- 3.9
- Impact Score
- 3.6
References
| Reference URL | Reference Tags |
|---|---|
| https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-dhcp-dos-pjPVReLU | Vendor Advisory |
Sources
| Source Name | Source URL |
|---|---|
| NIST | https://nvd.nist.gov/vuln/detail/CVE-2021-34737 |
| MITRE | https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-34737 |
History
| Created | Old Value | New Value | Data Type | Notes |
|---|---|---|---|---|
| 2022-05-10 06:54:00 | Added to TrackCVE | |||
| 2022-12-05 10:10:16 | psirt@cisco.com | ykramarz@cisco.com | CVE Assigner | updated |
| 2022-12-05 10:10:16 | 2021-09-09T05:15Z | 2021-09-09T05:15:11 | CVE Published Date | updated |
| 2022-12-05 10:10:16 | 2021-09-22T15:10:13 | CVE Modified Date | updated | |
| 2022-12-05 10:10:16 | Analyzed | Vulnerability Status | updated |