A vulnerability in the handling of internal resources necessary to bring up a large number of Layer 2 broadband remote access subscriber (BRAS) nodes in Juniper Networks Junos OS can cause the Access Node Control Protocol daemon (ANCPD) to crash and restart, leading to a Denial of Service (DoS) condition. Continued processing of spoofed subscriber nodes will create a sustained Denial of Service (DoS) condition. When the number of subscribers attempting to connect exceeds the configured maximum-discovery-table-entries value, the subscriber fails to map to an internal neighbor entry, causing the ANCPD process to crash.

This issue affects Juniper Networks Junos OS:

• 17.3 versions prior to 17.3R3-S12;
• 17.4 versions prior to 17.4R2-S13;
• 18.1 versions prior to 18.1R3-S13;
• 18.2 versions prior to 18.2R3-S8;
• 18.3 versions prior to 18.3R3-S5;
• 18.4 versions prior to 18.4R1-S8, 18.4R3-S8;
• 19.1 versions prior to 19.1R3-S4;
• 19.2 versions prior to 19.2R3-S2;
• 19.3 versions prior to 19.3R3-S1;
• 19.4 versions prior to 19.4R3-S1;
• 20.1 versions prior to 20.1R2;
• 20.2 versions prior to 20.2R2;
• 20.3 versions prior to 20.3R2.

Configurations that may be vulnerable to this issue are those where a maximum number of discovery table entries are configured. For example:

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-2021-0224 .
 

The following software releases have been updated to resolve this specific issue: Junos OS 17.3R3-S12, 17.4R2-S13, 18.2R3-S8, 18.4R1-S8, 18.4R3-S8, 19.1R3-S4, 19.2R3-S2, 19.3R3-S1, 19.4R3-S1, 20.1R2, 20.1R3, 20.2R2, 20.2R3, 20.3R2, 20.4R1, and all subsequent releases.

This issue is being tracked as  1544746 .
 

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-2021-0224 at cve.mitre.org