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2020-10 Security Bulletin: Junos OS: EX4300-MP/EX4600/QFX5K Series: High CPU load due to receipt of specific layer 2 frames in EVPN-VXLAN deployment. (CVE-2020-1687)

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Article ID: JSA11084 SECURITY_ADVISORIES Last Updated: 28 Oct 2020Version: 2.0
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 (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.
     

The example of the config stanza affected by this issue:

[protocols bgp ... family evpn]

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-2020-1687.

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, 19.1R2-S2, 19.1R3-S2, 19.2R1-S5, 19.2R2-S1, 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."

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