cisco-sa-iosxr-dhcp-dos-pjPVReLU: Cisco IOS XR Software DHCP Version 4 Server Denial of Service Vulnerability
First published: Wed Sep 08 2021(Updated: )
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. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. This advisory is available at the following link:https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-dhcp-dos-pjPVReLU This advisory is part of the September 2021 release of the Cisco IOS XR Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2021 Cisco IOS XR Software Security Advisory Bundled Publication.
Credit: This vulnerability was found during the resolution a Cisco TAC support case
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Cisco IOS XR Software | =7.1.3<ASR9K-X64 | ASR9K-X64 |
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Reference Links
Frequently Asked Questions
What is the vulnerability ID of the Cisco IOS XR Software DHCP version 4 server denial of service vulnerability?
The vulnerability ID is cisco-sa-iosxr-dhcp-dos-pjPVReLU.
What is the severity level of the Cisco IOS XR Software DHCP version 4 server denial of service vulnerability?
The severity level is medium with a CVSS score of 5.8.
How does the Cisco IOS XR Software DHCP version 4 server denial of service vulnerability occur?
The vulnerability occurs due to certain DHCPv4 messages being improperly validated by the dhcpd process, leading to a crash and denial of service condition.
Which Cisco product and version is affected by the DHCP version 4 server denial of service vulnerability?
The Cisco ASR9K-X64 running Cisco IOS XR Software version 7.1.3 and up to exclusive ASR9K-X64 versions are affected.
Is authentication required to exploit the Cisco IOS XR Software DHCP version 4 server denial of service vulnerability?
No, the vulnerability can be exploited by an unauthenticated, remote attacker.
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