Due to an improper Initialization vulnerability on Juniper Networks Junos OS QFX5100-96S devices with QFX 5e Series image installed, ddos-protection configuration changes will not take effect beyond the default DDoS (Distributed Denial of Service) settings when configured from the CLI. The DDoS protection (jddosd) daemon allows the device to continue to function while protecting the packet forwarding engine (PFE) during the DDoS attack. When this issue occurs, the default DDoS settings within the PFE apply, as CPU bound packets will be throttled and dropped in the PFE when the limits are exceeded.

To check if the device has this issue, the administrator can execute the following command to monitor the status of DDoS protection:

This issue affects only QFX5100-96S devices. No other products or platforms are affected by this issue.

This issue affects:

Juniper Networks Junos OS on QFX5100-96S:

• 17.3 versions prior to 17.3R3-S10;
• 17.4 versions prior to 17.4R3-S4;
• 18.1 versions prior to 18.1R3-S10;
• 18.2 versions prior to 18.2R3-S3;
• 18.3 versions prior to 18.3R3-S2;
• 18.4 versions prior to 18.4R2-S4, 18.4R3-S1;
• 19.1 versions prior to 19.1R3, 19.1R3-S4;
• 19.2 versions prior to 19.2R2;
• 19.3 versions prior to 19.3R3;
• 19.4 versions prior to 19.4R2;

The DDoS feature is enabled by default, there is no specific config stanza required to enable DDoS protection.

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-2021-0234 .

The following software releases have been updated to resolve this specific issue: 17.3R3-S10, 17.4R3-S4, 18.1R3-S10, 18.2R3-S3, 18.3R3-S2, 18.4R2-S4, 18.4R3-S1, 19.1R3, 19.1R3-S4, 19.2R2, 19.3R3, 19.4R2, 20.1R1, and all subsequent releases.

This issue is being tracked as 1486480 .

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

The following command can be used to enable ddos-protection manually:

root@device% /usr/sbin/jddosd -N &

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-2021-0234 at cve.mitre.org