In an EVPN/VXLAN scenario, if an IRB interface with a virtual gateway address (VGA) is configured on a PE, a traffic loop may occur upon receipt of specific IP multicast traffic. The traffic loop will cause interface traffic to increase abnormally, ultimately leading to a Denial of Service (DoS) in packet processing.

The following command could be used to monitor the interface traffic:

This issue affects Juniper Networks Junos OS on QFX10K Series:

• all versions prior to 17.3R3-S10;
• 17.4 versions prior to 17.4R2-S12, 17.4R3-S3;
• 18.1 versions prior to 18.1R3-S11;
• 18.2 versions prior to 18.2R3-S6;
• 18.3 versions prior to 18.3R3-S4;
• 18.4 versions prior to 18.4R2-S5, 18.4R3-S5;
• 19.1 versions prior to 19.1R1-S6, 19.1R2-S2, 19.1R3-S3;
• 19.2 versions prior to 19.2R1-S5, 19.2R3-S1;
• 19.3 versions prior to 19.3R2-S5, 19.3R3;
• 19.4 versions prior to 19.4R2-S2, 19.4R3;
• 20.1 versions prior to 20.1R2;
• 20.2 versions prior to 20.2R1-S2, 20.2R2.

This issue only affects the QFX10K Series (QFX10002, QFX10008). No other products or platforms are affected by this vulnerability.

A sample IRB configuration using virtual gateway addresses is shown below:

user@junos# show interfaces irb.1162 
virtual-gateway-accept-data;
family inet {
    address 192.168.190.125/25 {
        virtual-gateway-address 192.168.190.1;
    }
    address 192.168.190.253/25 {
        virtual-gateway-address 192.168.190.129;
    }
}
virtual-gateway-v4-mac 00:08:2b:03:05:07;

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-2021-0221 .
 

The following software releases have been updated to resolve this specific issue: Junos OS 17.3R3-S10, 17.4R2-S12, 17.4R3-S3, 18.1R3-S11, 18.2R3-S6, 18.3R3-S4, 18.4R2-S5, 18.4R3-S5, 19.1R1-S6, 19.1R2-S2, 19.1R3-S3, 19.2R1-S5, 19.2R3-S1, 19.3R2-S5, 19.3R3, 19.4R2-S2, 19.4R3, 20.1R2, 20.2R1-S2, 20.2R2, 20.3R1, and all subsequent releases.

This issue is being tracked as  1518537 .
 

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

2021-01-13: Initial Publication.
2021-01-19: Clarified that the issue only affects QFX10K Series switches.

• 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 Security Vulnerability - How to Contact the Juniper Networks Security Incident Response Team
• CVE-2021-0221 at cve.mitre.org