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AUSCERT External Security Bulletin Redistribution
JSA11119 - 2021-04 Security Bulletin: Junos OS: ANCPD core
when hitting maximum-discovery-table-entries limit
15 April 2021
AusCERT Security Bulletin Summary
Product: Junos OS: ANCPD core
Publisher: Juniper Networks
Operating System: Juniper
Impact/Access: Denial of Service -- Remote/Unauthenticated
CVE Names: CVE-2021-0224
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2021-04 Security Bulletin: Junos OS: ANCPD core when hitting maximum-discovery-table-entries limit (CVE-2021-0224)
Article ID : JSA11119
Last Updated: 14 Apr 2021
Version : 1.0
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.
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:
o 17.3 versions prior to 17.3R3-S12;
o 17.4 versions prior to 17.4R2-S13;
o 18.1 versions prior to 18.1R3-S13;
o 18.2 versions prior to 18.2R3-S8;
o 18.3 versions prior to 18.3R3-S5;
o 18.4 versions prior to 18.4R1-S8, 18.4R3-S8;
o 19.1 versions prior to 19.1R3-S4;
o 19.2 versions prior to 19.2R3-S2;
o 19.3 versions prior to 19.3R3-S1;
o 19.4 versions prior to 19.4R3-S1;
o 20.1 versions prior to 20.1R2;
o 20.2 versions prior to 20.2R2;
o 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 .
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 .
There are no viable workarounds for this issue.
Software releases or updates are available for download at https://
2021-04-14: Initial Publication.
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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