CVE-2021-34737
Cisco IOS XR Software DHCPv4 Server Denial of Service
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.
INFO
Published Date :
Sept. 9, 2021, 5:15 a.m.
Last Modified :
Nov. 7, 2023, 3:36 a.m.
Source :
[email protected]
Remotely Exploitable :
Yes !
Impact Score :
3.6
Exploitability Score :
3.9
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2021-34737.
| URL | Resource |
|---|---|
| https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-dhcp-dos-pjPVReLU | Vendor Advisory |
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2021-34737 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2021-34737 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by [email protected]
May. 14, 2024
Action Type Old Value New Value -
CVE Modified by [email protected]
Nov. 07, 2023
Action Type Old Value New Value Removed CVSS V3 Cisco Systems, Inc. AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L Added CVSS V3.1 Cisco Systems, Inc. AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L -
Initial Analysis by [email protected]
Sep. 22, 2021
Action Type Old Value New Value 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 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 Added CWE NIST CWE-476 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: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) 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 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: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:-:*:*:*:*:*:*:* cpe:2.3:h:cisco:ncs540-28z4c-sys-d:-:*:*:*:*:*:*:* cpe:2.3:h:cisco:ncs540-acc-sys:-:*:*:*:*:*:*:* cpe:2.3:h:cisco:ncs540x-12z16g-sys-a:-:*:*:*:*:*:*:* cpe:2.3:h:cisco:ncs540x-12z16g-sys-d:-:*:*:*:*:*:*:* cpe:2.3:h:cisco:ncs540x-16z4g8q2c-a:-:*:*:*:*:*:*:* cpe:2.3:h:cisco:ncs540x-16z4g8q2c-d:-:*:*:*:*:*:*:* cpe:2.3:h:cisco:ncs540x-acc-sys:-:*:*:*:*:*:*:* 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 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 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_5516:-:*:*:*:*:*:*:* -
CVE Modified by [email protected]
Sep. 09, 2021
Action Type Old Value New Value Changed 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. 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.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2021-34737 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2021-34737
weaknesses.
Exploit Prediction
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days.
0.15 }} 0.02%
score
0.51703
percentile