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

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Article ID: JSA11111 SECURITY_ADVISORIES Last Updated: 19 Jan 2021Version: 2.0
Product Affected:
This issue affects all versions of Junos OS. Affected platforms: QFX10K Series.
Problem:

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.
 

Solution:

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.
 

Workaround:
There are no known workarounds for this issue.
 
Implementation:
Software releases or updates are available for download at https://www.juniper.net/support/downloads/.
 
Modification History:
2021-01-13: Initial Publication.
2021-01-19: Clarified that the issue only affects QFX10K Series switches.

CVSS Score:
6.5 (CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
Severity Level:
Medium
Severity Assessment:
Information for how Juniper Networks uses CVSS can be found at KB 16446 "Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories."

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