CVE-2020-1687: On Juniper Networks EX4300-MP Series, EX4600 Series and QFX5K Series deployed in (Ethernet VPN) EVPN-(Virtual Extensible LAN) VXLAN configuration, rec...

Description

On Juniper Networks EX4300-MP Series, EX4600 Series and QFX5K Series deployed in (Ethernet VPN) EVPN-(Virtual Extensible LAN) VXLAN configuration, receipt of a stream of specific VXLAN encapsulated layer 2 frames can cause high CPU load, which could lead to network protocol operation issue and traffic interruption. This issue affects devices that are configured as a Layer 2 or Layer 3 gateway of an EVPN-VXLAN deployment. The offending layer 2 frames that cause the issue originate from a different access switch that get encapsulated within the same EVPN-VXLAN domain. 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 19.1R2-S2, 19.1R3-S2; 19.2 versions prior to 19.2R1-S5, 19.2R2-S1, 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.

Metrics

CVSS 3.1

6.5/10

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

0.49%

38.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-400

Affected Software

Vendor	Product	Versions	Update
Juniper	Junos	17.3	—
Juniper	Junos	17.4	—
Juniper	Junos	18.1	—
Juniper	Junos	18.2	—
Juniper	Junos	18.3	—
Juniper	Junos	18.4	—
Juniper	Junos	19.1	—
Juniper	Junos	19.2	—
Juniper	Junos	19.3	—
Juniper	Junos	19.4	R1
Juniper	Junos	20.1	R1

References

https://kb.juniper.net/JSA11084Vendor Advisory
https://kb.juniper.net/JSA11084Vendor Advisory

Timeline

Published: Oct 16, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-1687?

On Juniper Networks EX4300-MP Series, EX4600 Series and QFX5K Series deployed in (Ethernet VPN) EVPN-(Virtual Extensible LAN) VXLAN configuration, receipt of a stream of specific VXLAN encapsulated layer 2 frames can cause high CPU load, which could lead to network protocol operation issue and traffic interruption. This issue affects devices that are configured as a Layer 2 or Layer 3 gateway of an EVPN-VXLAN deployment. The offending layer 2 frames that cause the issue originate from a different access switch that get encapsulated within the same EVPN-VXLAN domain. 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 19.1R2-S2, 19.1R3-S2; 19.2 versions prior to 19.2R1-S5, 19.2R2-S1, 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.

How severe is CVE-2020-1687?

CVE-2020-1687 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.49% probability of exploitation in the next 30 days.

How do I fix CVE-2020-1687?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.