CVE-2021-0236 Explained : Impact and Mitigation

A Denial of Service (DoS) vulnerability has been identified in Juniper Networks Junos OS and Junos OS Evolved. This vulnerability, assigned CVE-2021-0236, affects the Routing Protocol Daemon (RPD) service and can be exploited by specially crafted BGP packets, leading to service crashes and restarts.

Understanding CVE-2021-0236

This section delves into the impact, technical details, and mitigation strategies related to the CVE-2021-0236 vulnerability.

What is CVE-2021-0236?

CVE-2021-0236 is a Denial of Service (DoS) vulnerability in Juniper Networks Junos OS and Junos OS Evolved. The flaw lies in the Routing Protocol Daemon (RPD) service's improper handling of specific BGP packets, which could trigger service disruptions.

The Impact of CVE-2021-0236

The vulnerability could be exploited by malicious actors to crash and restart the RPD service by sending crafted BGP packets. This could result in a sustained Denial of Service (DoS) condition, impacting network availability.

Technical Details of CVE-2021-0236

Here are the technical specifics of the CVE-2021-0236 vulnerability:

Vulnerability Description

Juniper Networks Junos OS and Junos OS Evolved are susceptible to crashes in the RPD service when processing specific BGP packets related to Multiprotocol BGP (MP-BGP) VPNv6 FlowSpec deployments.

Affected Systems and Versions

Juniper Networks Junos OS versions impacted: 18.4 to 20.3
Juniper Networks Junos OS Evolved versions impacted: 18.4R1-EVO to 20.3R2-EVO

Exploitation Mechanism

Juniper SIRT has not detected any instances of malicious exploitation of this vulnerability.

Mitigation and Prevention

Learn how to address and prevent the CVE-2021-0236 vulnerability in Juniper Networks Junos OS and Junos OS Evolved:

Immediate Steps to Take

Juniper advises updating affected software versions to resolve the issue. The following releases have been patched:

Junos OS: 18.4R1-S8, 18.4R2-S7, 18.4R3-S7, and more
Junos OS Evolved: 20.3R2-EVO, 20.4R1-EVO, and subsequent releases

Long-Term Security Practices

Ensure regular software updates and follow Juniper's security advisories to stay protected against potential vulnerabilities.

Patching and Updates

Apply the recommended software updates provided by Juniper Networks to mitigate the CVE-2021-0236 vulnerability.