Due to a vulnerability in DDoS protection in Juniper Networks Junos OS and Junos OS Evolved on QFX5K Series switches in a VXLAN configuration, instability might be experienced in the underlay network as a consequence of exceeding the default ddos-protection aggregate threshold. If an attacker on a client device on the overlay network sends a high volume of specific, legitimate traffic in the overlay network, due to an improperly detected DDoS violation, the leaf might not process certain L2 traffic, sent by spines in the underlay network. Continued receipt and processing of the high volume traffic will sustain the Denial of Service (DoS) condition.

This issue affects:

Juniper Networks Junos OS on QFX5K Series:

• 17.3 versions prior to 17.3R3-S11;
• 17.4 versions prior to 17.4R3-S5;
• 18.1 versions prior to 18.1R3-S13;
• 18.2 versions prior to 18.2R2-S8, 18.2R3-S8;
• 18.3 versions prior to 18.3R3-S5;
• 18.4 versions prior to 18.4R1-S8, 18.4R2-S6, 18.4R3-S6;
• 19.1 versions prior to 19.1R3-S4;
• 19.2 versions prior to 19.2R1-S6, 19.2R3-S2;
• 19.3 versions prior to 19.3R3-S2;
• 19.4 versions prior to 19.4R2-S4, 19.4R3-S1;
• 20.1 versions prior to 20.1R2;
• 20.2 versions prior to 20.2R2;
• 20.3 versions prior to 20.3R1-S2, 20.3R2.

Juniper Networks Junos OS Evolved on QFX5220:

• All versions prior to 20.3R2-EVO.

An example of a configuration affected by this issue is shown below:

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-2021-0259 .
 

The following software releases have been updated to resolve this specific issue:

Junos OS: 17.3R3-S11, 17.4R3-S5, 18.1R3-S13, 18.2R2-S8, 18.2R3-S8, 18.3R3-S5, 18.4R1-S8, 18.4R2-S6, 18.4R3-S6, 19.1R3-S4, 19.2R1-S6, 19.2R3-S2, 19.3R3-S2, 19.4R2-S4, 19.4R3-S1, 20.1R2, 20.2R2, 20.3R1-S2, 20.3R2, 20.4R1, and all subsequent releases.

Junos OS Evolved: 20.3R2-EVO, 20.4R1-EVO, and all subsequent releases.

This issue is being tracked as  1499681 .
 

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

2021-04-14: Initial Publication.

• KB16613: Overview of the Juniper Networks SIRT Quarterly Security Bulletin Publication Process [juniper.net]
• KB16765: In which releases are vulnerabilities fixed? [juniper.net]
• KB16446: Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories [juniper.net]
• Report a Security Vulnerability - How to Contact the Juniper Networks Security Incident Response Team
• CVE-2021-0259 at cve.mitre.org