CVE-2021-0224: A vulnerability in the handling of internal resources necessary to bring up a large number of Layer 2 broadband remote access subscriber (BRAS) nodes ...

Description

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: All 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.

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

0.38%

29.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

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
Juniper	Junos	20.2	R1
Juniper	Junos	20.3	R1

References

https://kb.juniper.net/JSA11119Vendor Advisory
https://kb.juniper.net/JSA11119Vendor Advisory

Timeline

Published: Apr 22, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-0224?

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: All 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.

How severe is CVE-2021-0224?

CVE-2021-0224 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.38% probability of exploitation in the next 30 days.

How do I fix CVE-2021-0224?

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.