CVE-2021-0243 : Security Advisory and Response
Learn about CVE-2021-0243, a vulnerability in Juniper Networks Junos OS on EX4300 switches that allows traffic to exceed policer limits, potentially leading to a Denial of Service (DoS) condition.
A vulnerability has been identified in Juniper Networks Junos OS on EX4300 switches that allows matching traffic to exceed set policer limits in the firewall policer, potentially resulting in a Denial of Service (DoS) condition due to the failure of the policer discard action on Layer 2 ports. This article provides detailed insights into CVE-2021-0243.
Understanding CVE-2021-0243
In this section, you will gain an understanding of the nature of CVE-2021-0243 and its potential impact.
What is CVE-2021-0243?
CVE-2021-0243 is related to the improper handling of unexpected data in the firewall policer of Juniper Networks Junos OS on EX4300 switches.
The Impact of CVE-2021-0243
The vulnerability allows traffic to bypass set policer limits, leading to a limited Denial of Service (DoS) condition.
Technical Details of CVE-2021-0243
This section delves into the technical aspects of CVE-2021-0243, including the vulnerability description, affected systems, and exploitation mechanism.
Vulnerability Description
When the firewall policer discard action fails on a Layer 2 port, it allows traffic to pass even if it exceeds set policer limits, causing potential denial of service.
Affected Systems and Versions
Juniper Networks Junos OS on EX4300 switches prior to various versions including 17.3R3-S10, 17.4R3-S3, 18.1R3-S11, and more are affected.
Exploitation Mechanism
No malicious exploitation has been reported by Juniper SIRT regarding this vulnerability.
Mitigation and Prevention
This section provides guidance on addressing and preventing the impact of CVE-2021-0243.
Immediate Steps to Take
Ensure your Juniper Networks Junos OS is updated to the recommended versions to mitigate the vulnerability's risk.
Long-Term Security Practices
Regularly update your Junos OS software to the latest releases that include patches for CVE-2021-0243.
Patching and Updates
Juniper Networks has released updates including versions 17.3R3-S10, 17.4R3-S3, 18.1R3-S11, and subsequent releases to address this issue.