2021-01 Security Bulletin: Junos OS: QFX10K Series: Traffic loop Denial of Service (DoS) upon receipt of specific IP multicast traffic (CVE-2021-0221)

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:

user@junos> monitor interface traffic
Interface Link Input packets (pps) Output packets (pps)
et-0/0/1 Up 6492089274364 (70994959) 6492089235319 (70994956)
et-0/0/25 Up 343458103 (1) 156844 (0)
ae0 Up 9132519197257 (70994959) 9132519139454 (70994956)

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.

Knowledge Base