2020-10 Security Bulletin: Junos OS: EX4300-MP/EX4600/QFX5K Series: High CPU load due to receipt of specific layer 2 frames when deployed in a Virtual Chassis configuration (CVE-2020-1689)

Product Affected:

This issue affects Junos OS 17.3, 17.4, 18.1, 18.2, 18.3, 18.4, 19.1, 19.2, 19.3, 19.4, 20.1. Affected platforms: EX4300-MP Series, EX4600Series, QFX5K Series.

Problem:

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:

user@switch> show virtual-chassis status
Virtual Chassis Mode: Enabled

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.

Solution:

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.

Workaround:

There are no viable workarounds for this issue.

Implementation:

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

Modification History:

2020-10-14: Initial Publication.

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."

Knowledge Base