CVE-2021-0224
Junos OS: ANCPD core when hitting maximum-discovery-table-entries limit
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.
Attack profile
How easy it is to exploit
- Attack vector
- Adjacent network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
Junos OS: ANCPD core when hitting maximum-discovery-table-entries limit
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.
- Record
CVE-2021-0224- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-770
- Updated
- 2026-11-02
EUVDEUVD-2021-2843
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.
- Record
EUVD-2021-2843- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-m9hm-283g-g7rx No score
A vulnerability in the handling of internal resources necessary to bring up a large number of...
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.
- Record
GHSA-m9hm-283g-g7rx- Weakness
- CWE-770
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2021-0224- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - CVSS 2.0
- 3.3 Low
AV:A/AC:L/Au:N/C:N/I:N/A:P - Weakness
- CWE-770
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases, published | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-0224 is a medium vulnerability (CVSS 6.5) in Juniper Junos, published April 22, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.38%, the 32nd percentile. No source names a fixed version.