How should we interpret CVSS severity scores?

CVSS estimates technical severity, but it does not automatically equal business risk. Prioritize using context like internet exposure, asset criticality, known exploitation, and whether compensating controls exist. A Medium CVSS on an exposed production system can be more urgent than a Critical on an isolated non-production host.

Vulnerability Database

Q: What is a Vulnerability (CVE) and why does it matter?

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

Q: What's the difference between a vulnerability, an exploit, and a zero-day?

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. Risk increases sharply when exploitation becomes reliable or widespread.

Q: Why do vulnerabilities keep reappearing in our environment?

Recurring findings usually come from incomplete asset discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host.

Q: How do we prioritize remediation without burning out the team?

Use a repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress so remediation is steady, not reactive.

Q: How can SynScan help reduce vulnerability risk over time?

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.

346,508

Total vulnerabilities in the database

CVE-2021-0217 — juniper / junos

Allocation of Resources Without Limits or Throttling

A vulnerability in processing of certain DHCP packets from adjacent clients on EX Series and QFX Series switches running Juniper Networks Junos OS with DHCP local/relay server configured may lead to exhaustion of DMA memory causing a Denial of Service (DoS). Over time, exploitation of this vulnerability may cause traffic to stop being forwarded, or to crashing of the fxpc process. When Packet DMA heap utilization reaches 99%, the system will become unstable. Packet DMA heap utilization can be monitored through the following command: user@junos# request pfe execute target fpc0 timeout 30 command "show heap" ID Base Total(b) Free(b) Used(b) % Name -- ---------- ----------- ----------- ----------- --- ----------- 0 213301a8 536870488 387228840 149641648 27 Kernel 1 91800000 8388608 3735120 4653488 55 DMA 2 92000000 75497472 74452192 1045280 1 PKT DMA DESC 3 d330000 335544320 257091400 78452920 23 Bcm_sdk 4 96800000 184549376 2408 184546968 99 Packet DMA <--- 5 903fffe0 20971504 20971504 0 0 Blob An indication of the issue occurring may be observed through the following log messages: Dec 10 08:07:00.124 2020 hostname fpc0 brcm_pkt_buf_alloc:523 (buf alloc) failed allocating packet buffer Dec 10 08:07:00.126 2020 hostname fpc0 (buf alloc) failed allocating packet buffer Dec 10 08:07:00.128 2020 hostname fpc0 brcm_pkt_buf_alloc:523 (buf alloc) failed allocating packet buffer Dec 10 08:07:00.130 2020 hostnameC fpc0 (buf alloc) failed allocating packet buffer This issue affects Juniper Networks Junos OS on EX Series and QFX Series: 17.4R3 versions prior to 17.4R3-S3; 18.1R3 versions between 18.1R3-S6 and 18.1R3-S11; 18.2R3 versions prior to 18.2R3-S6; 18.3R3 versions prior to 18.3R3-S4; 18.4R2 versions prior to 18.4R2-S5; 18.4R3 versions prior to 18.4R3-S6; 19.1 versions between 19.1R2 and 19.1R3-S3; 19.2 versions prior to 19.2R3-S1; 19.3 versions prior to 19.3R2-S5, 19.3R3; 19.4 versions prior to 19.4R2-S2, 19.4R3; 20.1 versions prior to 20.1R2; 20.2 versions prior to 20.2R1-S2, 20.2R2. Junos OS versions prior to 17.4R3 are unaffected by this vulnerability.

Published: Jan 15, 2021
Updated: Nov 16, 2025
CVE: CVE-2021-0217
Severity: High
Exploit:

CVSS v3:

Severity: High
Score: 7.4
AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

CVSS v2:

Severity: Low
Score: 3.3
AV:A/AC:L/Au:N/C:N/I:N/A:P

CWEs:

Affected Software
References

Software	From	Fixed in
juniper / junos	17.4-r3	17.4-r3.x
juniper / junos	17.4-r3-s1	17.4-r3-s1.x
juniper / junos	17.4-r3-s2	17.4-r3-s2.x
juniper / junos	18.1-r3-s10	18.1-r3-s10.x
juniper / junos	18.1-r3-s9	18.1-r3-s9.x
juniper / junos	18.1-r3-s7	18.1-r3-s7.x
juniper / junos	18.1-r3-s8	18.1-r3-s8.x
juniper / junos	18.2-r3	18.2-r3.x
juniper / junos	18.2-r3-s1	18.2-r3-s1.x
juniper / junos	18.2-r3-s2	18.2-r3-s2.x
juniper / junos	18.2-r3-s4	18.2-r3-s4.x
juniper / junos	18.2-r3-s3	18.2-r3-s3.x
juniper / junos	18.2-r3-s5	18.2-r3-s5.x
juniper / junos	18.3-r3-s2	18.3-r3-s2.x
juniper / junos	18.3-r3-s3	18.3-r3-s3.x
juniper / junos	18.3-r3-s1	18.3-r3-s1.x
juniper / junos	18.3-r3	18.3-r3.x
juniper / junos	18.4-r2-s2	18.4-r2-s2.x
juniper / junos	18.4-r2-s1	18.4-r2-s1.x
juniper / junos	18.4-r2	18.4-r2.x
juniper / junos	18.4-r2-s3	18.4-r2-s3.x
juniper / junos	18.4-r2-s4	18.4-r2-s4.x
juniper / junos	19.1-r2-s1	19.1-r2-s1.x
juniper / junos	19.1-r3	19.1-r3.x
juniper / junos	19.1-r3-s1	19.1-r3-s1.x
juniper / junos	19.1-r3-s2	19.1-r3-s2.x
juniper / junos	19.2-r2	19.2-r2.x
juniper / junos	19.2-r3	19.2-r3.x
juniper / junos	19.2-r1-s4	19.2-r1-s4.x
juniper / junos	19.2-r1	19.2-r1.x
juniper / junos	19.2	19.2.x
juniper / junos	19.2-r1-s1	19.2-r1-s1.x
juniper / junos	19.2-r1-s2	19.2-r1-s2.x
juniper / junos	19.2-r1-s3	19.2-r1-s3.x
juniper / junos	19.3	19.3.x
juniper / junos	19.3-r1	19.3-r1.x
juniper / junos	19.3-r2-s1	19.3-r2-s1.x
juniper / junos	19.3-r1-s1	19.3-r1-s1.x
juniper / junos	19.3-r2	19.3-r2.x
juniper / junos	19.3-r2-s4	19.3-r2-s4.x
juniper / junos	19.3-r2-s3	19.3-r2-s3.x
juniper / junos	19.3-r2-s2	19.3-r2-s2.x
juniper / junos	19.4-r1-s1	19.4-r1-s1.x
juniper / junos	19.4-r2	19.4-r2.x
juniper / junos	19.4-r2-s1	19.4-r2-s1.x
juniper / junos	19.4-r1-s2	19.4-r1-s2.x
juniper / junos	19.4-r1	19.4-r1.x
juniper / junos	20.1-r1-s1	20.1-r1-s1.x
juniper / junos	20.1-r1	20.1-r1.x
juniper / junos	20.1-r1-s2	20.1-r1-s2.x
juniper / junos	20.1-r1-s3	20.1-r1-s3.x
juniper / junos	20.2-r1	20.2-r1.x
juniper / junos	20.2-r1-s1	20.2-r1-s1.x

https://kb.juniper.net/JSA11107

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Frequently Asked Questions

What is a Vulnerability (CVE) and why does it matter?

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.

Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.

Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.