CVE-2021-34767 : Vulnerability Insights and Analysis
Learn about CVE-2021-34767, a high-severity vulnerability in Cisco IOS XE Software for Catalyst 9800 Series Wireless Controllers, allowing an unauthenticated attacker to create a denial of service condition.
A vulnerability in IPv6 traffic processing of Cisco IOS XE Wireless Controller Software for Cisco Catalyst 9000 Family Wireless Controllers could allow an unauthenticated, adjacent attacker to cause a Layer 2 (L2) loop in a configured VLAN, resulting in a denial of service (DoS) condition for that VLAN.
Understanding CVE-2021-20657
This vulnerability affects Cisco IOS XE Software and is considered to have a high severity level with a base score of 7.4.
What is CVE-2021-20657?
The vulnerability in IPv6 traffic processing of Cisco IOS XE Wireless Controller Software for Cisco Catalyst 9000 Family Wireless Controllers allows an unauthenticated attacker to create a denial of service condition by causing a Layer 2 loop in a configured VLAN.
The Impact of CVE-2021-20657
Exploiting this vulnerability could lead to traffic drops in the affected VLAN, potentially causing a Denial of Service (DoS) condition for that VLAN.
Technical Details of CVE-2021-20657
This section provides insight into the vulnerability, affected systems, and how it can be exploited.
Vulnerability Description
The vulnerability is caused by a logic error in processing specific link-local IPv6 traffic, allowing an attacker to send crafted IPv6 packets through the wired interface of the affected device.
Affected Systems and Versions
The affected product is Cisco IOS XE Software, and the specific version details are not applicable (n/a).
Exploitation Mechanism
An attacker can exploit this vulnerability by sending a crafted IPv6 packet that triggers a Layer 2 loop, leading to traffic drops in the affected VLAN.
Mitigation and Prevention
It is essential to take immediate steps to mitigate the risk and prevent potential exploitation.
Immediate Steps to Take
Ensure that VLAN configurations are secure, monitor network traffic for any abnormal patterns, and restrict network access to prevent unauthorized traffic.
Long-Term Security Practices
Implement security best practices such as regular security updates, network segmentation, and access control measures to enhance overall network security.
Patching and Updates
Apply patches provided by Cisco to address this vulnerability and ensure that systems are up to date with the latest security fixes.