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2021-04 Security Bulletin: Junos OS: ANCPD core when hitting maximum-discovery-table-entries limit (CVE-2021-0224)

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Article ID: JSA11119 SECURITY_ADVISORIES Last Updated: 14 Apr 2021Version: 1.0
Product Affected:
This issue affects Junos OS all versions prior to 17.3R3-S12, 17.4, 18.1, 18.2, 18.3, 18.4, 19.1, 19.2, 19.3, 19.4, 20.1, 20.2, 20.3.
Problem:

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:

[protocols ancp maximum-discovery-table-entries]


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.
 

Solution:

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.
 

Workaround:
There are no viable workarounds for this issue.
 
Implementation:
Software releases or updates are available for download at https://support.juniper.net/support/downloads/
 
Modification History:
2021-04-14: 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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