On Juniper Networks EX4300-MP Series, EX4600 Series and QFX5K Series deployed in a Virtual Chassis configuration, receipt of a stream of specific layer 2 frames can cause high CPU load, which could lead to traffic interruption.

This issue does not occur when the device is deployed in Stand Alone configuration.

The offending layer 2 frame packets can originate only from within the broadcast domain where the device is connected.
 

This issue affects Juniper Networks Junos OS on EX4300-MP Series, EX4600 Series and QFX5K Series:

• 17.3 versions prior to 17.3R3-S9;
• 17.4 versions prior to 17.4R2-S11, 17.4R3-S2, 17.4R3-S3;
• 18.1 versions prior to 18.1R3-S11;
• 18.2 versions prior to 18.2R3-S5;
• 18.3 versions prior to 18.3R2-S4, 18.3R3-S3;
• 18.4 versions prior to 18.4R2-S5, 18.4R3-S4;
• 19.1 versions prior to 19.1R3-S2;
• 19.2 versions prior to 19.2R1-S5, 19.2R3;
• 19.3 versions prior to 19.3R2-S4, 19.3R3;
• 19.4 versions prior to 19.4R1-S3, 19.4R2-S1, 19.4R3;
• 20.1 versions prior to 20.1R1-S3, 20.1R2.
   

To check if virtual chassis is configured, the administrator can run the following command:

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

This issue was seen during production usage.

This issue has been assigned CVE-2020-1689 .

The following software releases have been updated to resolve this specific issue: Junos OS 17.3R3-S9, 17.4R2-S11, 17.4R3-S2, 17.4R3-S3, 18.1R3-S11, 18.2R3-S5, 18.3R2-S4, 18.3R3-S3, 18.4R2-S5, 18.4R3-S4, 19.1R3-S2, 19.2R1-S5, 19.2R3, 19.3R2-S4, 19.3R3, 19.4R1-S3, 19.4R2-S1, 19.4R3, 20.1R1-S3, 20.1R2, 20.2R1, and all subsequent releases.

This issue is being tracked as 1495890 .

Software releases or updates are available for download at https://www.juniper.net/support/downloads/ .

There are no viable workarounds for this issue.

• KB16613: Overview of the Juniper Networks SIRT Quarterly Security Bulletin Publication Process [juniper.net]
• KB16765: In which releases are vulnerabilities fixed? [juniper.net]
• KB16446: Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories [juniper.net]
• Report a Vulnerability - How to Contact the Juniper Networks Security Incident Response Team
• CVE-2020-1689 at cve.mitre.org