CVE-2021-34737: cisco cisco ios xr software NULL Pointer Dereference

Vulnerability summary

CVE-2021-34737 is a high (CVSS 7.5) NULL Pointer Dereference vulnerability in cisco cisco ios xr software. EPSS estimates a 1.33% chance of exploitation in the next 30 days, higher than 70.5% of scored vulnerabilities.

Timeline

1. 09-09-2021
   PublishedVulnerability first disclosed.
2. 07-11-2024
   Last modifiedVulnerability information updated.

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.

• CWE-476NULL Pointer DereferenceThe product dereferences a pointer that it expects to be valid but is NULL.