Vulnerability 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.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Cisco | Ios Xr | < 7.3.2 |
| Cisco | Asr 9000V-V2 | - |
| Cisco | Asr 9001 | - |
| Cisco | Asr 9006 | - |
| Cisco | Asr 9010 | - |
| Cisco | Asr 9901 | - |
| Cisco | Asr 9902 | - |
| Cisco | Asr 9903 | - |
| Cisco | Asr 9904 | - |
| Cisco | Asr 9906 | - |
| Cisco | Asr 9910 | - |
| Cisco | Asr 9912 | - |
| Cisco | Asr 9922 | - |
| Cisco | Ios Xrv 9000 | - |
| Cisco | Ncs540-12Z20G-Sys-A | - |
| Cisco | Ncs540-12Z20G-Sys-D | - |
| Cisco | Ncs540-24Z8Q2C-M | - |
| Cisco | Ncs540-24Z8Q2C-Sys | - |
| Cisco | Ncs540-28Z4C-Sys-A | - |
| Cisco | Ncs540-28Z4C-Sys-D | - |
Related Weaknesses (CWE)
References
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iVendor Advisory
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iVendor Advisory
FAQ
What is CVE-2021-34737?
CVE-2021-34737 is a vulnerability with a CVSS score of 5.8 (MEDIUM). 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...
How severe is CVE-2021-34737?
CVE-2021-34737 has been rated MEDIUM with a CVSS base score of 5.8/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2021-34737?
Check the references section above for vendor advisories and patch information. Affected products include: Cisco Ios Xr, Cisco Asr 9000V-V2, Cisco Asr 9001, Cisco Asr 9006, Cisco Asr 9010.