CVE-2021-31361 Explained : Impact and Mitigation

A detailed article outlining the CVE-2021-31361 vulnerability found in Juniper Networks Junos OS affecting QFX Series and PTX Series.

Understanding CVE-2021-31361

This section provides insights into the vulnerability, its impact, affected systems, and more.

What is CVE-2021-31361?

CVE-2021-31361 involves an Improper Check for Unusual or Exceptional Conditions vulnerability in Juniper Networks Junos OS, leading to increased FPC CPU utilization due to specific VXLAN encapsulated packets.

The Impact of CVE-2021-31361

The vulnerability allows unauthenticated attackers to trigger a partial Denial of Service (DoS) on affected Junos OS versions for QFX Series and PTX Series.

Technical Details of CVE-2021-31361

This section dives into the technical aspects of the vulnerability, including the description, affected systems, and exploitation mechanism.

Vulnerability Description

The flaw in Junos OS allows attackers to cause FPC CPU spike using VXLAN encapsulated packets, resulting in a DoS condition.

Affected Systems and Versions

QFX Series and PTX Series running Junos OS versions listed in the configurations are vulnerable to this exploit.

Exploitation Mechanism

Malicious actors can exploit this vulnerability by sending specific IP traffic while utilizing VXLAN encapsulation.

Mitigation and Prevention

This section discusses the steps to mitigate the CVE-2021-31361 vulnerability on affected systems.

Immediate Steps to Take

Update Junos OS on QFX Series and PTX Series to the patched versions provided by Juniper Networks to prevent exploitation of this vulnerability.

Long-Term Security Practices

Regularly update and patch Junos OS to the latest recommended software releases to ensure protection against known vulnerabilities.

Patching and Updates

Refer to the Juniper Networks advisory (JSA11223) for detailed information on the software releases that address this vulnerability.