CVE-2020-1665 | Junos OS: MX series/EX9200 Series: IPv6 DDoS protection does not work as expected.

On Juniper Networks MX Series and EX9200 Series, in a certain condition the IPv6 Distributed Denial of Service (DDoS) protection might not take affect when it reaches the threshold condition. The DDoS protection allows the device to continue to function while it is under DDoS attack, protecting both the Routing Engine (RE) and the Flexible PIC Concentrator (FPC) during the DDoS attack. When this issue occurs, the RE and/or the FPC can become overwhelmed, which could disrupt network protocol operations and/or interrupt traffic. This issue does not affect IPv4 DDoS protection. This issue affects MX Series and EX9200 Series with Trio-based PFEs (Packet Forwarding Engines). Please refer to https://kb.juniper.net/KB25385 for the list of Trio-based PFEs. This issue affects Juniper Networks Junos OS on MX series and EX9200 Series: 17.2 versions prior to 17.2R3-S4; 17.2X75 versions prior to 17.2X75-D102, 17.2X75-D110; 17.3 versions prior to 17.3R3-S8; 17.4 versions prior to 17.4R2-S11, 17.4R3-S2; 18.2 versions prior to 18.2R2-S7, 18.2R3, 18.2R3-S3; 18.2X75 versions prior to 18.2X75-D30; 18.3 versions prior to 18.3R2-S4, 18.3R3-S2.

Published: 2020-10-16 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-1665 is rated Moderate Risk (45.2/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 1.26%). EPSS rose +1.03% over the last day, indicating growing attacker interest. Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2020-1665

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.23% 1.26% +1.03%
2 2025-03-30 0.37% 0.23% -0.14%
3 2025-03-29 — 0.37% —

Full EPSS history (9 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-1665

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 3.9 1.4 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2020-1665

Affected software / configurations for CVE-2020-1665

Vendor Product Version Raw CPE
juniper junos 17.2 cpe:2.3:o:juniper:junos:17.2:-:*:*:*:*:*:*
juniper junos 17.2 cpe:2.3:o:juniper:junos:17.2:r1:*:*:*:*:*:*
juniper junos 17.2 cpe:2.3:o:juniper:junos:17.2:r1-s1:*:*:*:*:*:*
juniper junos 17.2 cpe:2.3:o:juniper:junos:17.2:r1-s2:*:*:*:*:*:*
juniper junos 17.2 cpe:2.3:o:juniper:junos:17.2:r1-s3:*:*:*:*:*:*
juniper junos 17.2 cpe:2.3:o:juniper:junos:17.2:r1-s4:*:*:*:*:*:*
juniper junos 17.2 cpe:2.3:o:juniper:junos:17.2:r1-s5:*:*:*:*:*:*
juniper junos 17.2 cpe:2.3:o:juniper:junos:17.2:r1-s7:*:*:*:*:*:*
juniper junos 17.2 cpe:2.3:o:juniper:junos:17.2:r1-s8:*:*:*:*:*:*
juniper junos 17.2 cpe:2.3:o:juniper:junos:17.2:r2:*:*:*:*:*:*
juniper junos 17.2 cpe:2.3:o:juniper:junos:17.2:r2-s11:*:*:*:*:*:*
juniper junos 17.2 cpe:2.3:o:juniper:junos:17.2:r2-s6:*:*:*:*:*:*
juniper junos 17.2 cpe:2.3:o:juniper:junos:17.2:r2-s7:*:*:*:*:*:*
juniper junos 17.2 cpe:2.3:o:juniper:junos:17.2:r3-s1:*:*:*:*:*:*
juniper junos 17.2 cpe:2.3:o:juniper:junos:17.2:r3-s2:*:*:*:*:*:*
juniper junos 17.2 cpe:2.3:o:juniper:junos:17.2:r3-s3:*:*:*:*:*:*
juniper junos 17.2x75 cpe:2.3:o:juniper:junos:17.2x75:-:*:*:*:*:*:*
juniper junos 17.2x75 cpe:2.3:o:juniper:junos:17.2x75:d50:*:*:*:*:*:*
juniper junos 17.2x75 cpe:2.3:o:juniper:junos:17.2x75:d70:*:*:*:*:*:*
juniper junos 17.2x75 cpe:2.3:o:juniper:junos:17.2x75:d92:*:*:*:*:*:*
juniper junos 17.3 cpe:2.3:o:juniper:junos:17.3:-:*:*:*:*:*:*
juniper junos 17.3 cpe:2.3:o:juniper:junos:17.3:r1-s1:*:*:*:*:*:*
juniper junos 17.3 cpe:2.3:o:juniper:junos:17.3:r2:*:*:*:*:*:*
juniper junos 17.3 cpe:2.3:o:juniper:junos:17.3:r2-s1:*:*:*:*:*:*
juniper junos 17.3 cpe:2.3:o:juniper:junos:17.3:r2-s2:*:*:*:*:*:*
juniper junos 17.3 cpe:2.3:o:juniper:junos:17.3:r2-s3:*:*:*:*:*:*
juniper junos 17.3 cpe:2.3:o:juniper:junos:17.3:r2-s4:*:*:*:*:*:*
juniper junos 17.3 cpe:2.3:o:juniper:junos:17.3:r2-s5:*:*:*:*:*:*
juniper junos 17.3 cpe:2.3:o:juniper:junos:17.3:r3:-:*:*:*:*:*
juniper junos 17.3 cpe:2.3:o:juniper:junos:17.3:r3-s1:*:*:*:*:*:*
juniper junos 17.3 cpe:2.3:o:juniper:junos:17.3:r3-s2:*:*:*:*:*:*
juniper junos 17.3 cpe:2.3:o:juniper:junos:17.3:r3-s3:*:*:*:*:*:*
juniper junos 17.3 cpe:2.3:o:juniper:junos:17.3:r3-s4:*:*:*:*:*:*
juniper junos 17.3 cpe:2.3:o:juniper:junos:17.3:r3-s7:*:*:*:*:*:*
juniper junos 17.4 cpe:2.3:o:juniper:junos:17.4:-:*:*:*:*:*:*
juniper junos 17.4 cpe:2.3:o:juniper:junos:17.4:r1:*:*:*:*:*:*
juniper junos 17.4 cpe:2.3:o:juniper:junos:17.4:r1-s1:*:*:*:*:*:*
juniper junos 17.4 cpe:2.3:o:juniper:junos:17.4:r1-s2:*:*:*:*:*:*
juniper junos 17.4 cpe:2.3:o:juniper:junos:17.4:r1-s4:*:*:*:*:*:*
juniper junos 17.4 cpe:2.3:o:juniper:junos:17.4:r1-s5:*:*:*:*:*:*
juniper junos 17.4 cpe:2.3:o:juniper:junos:17.4:r1-s6:*:*:*:*:*:*
juniper junos 17.4 cpe:2.3:o:juniper:junos:17.4:r1-s7:*:*:*:*:*:*
juniper junos 17.4 cpe:2.3:o:juniper:junos:17.4:r2:*:*:*:*:*:*
juniper junos 17.4 cpe:2.3:o:juniper:junos:17.4:r2-s1:*:*:*:*:*:*
juniper junos 17.4 cpe:2.3:o:juniper:junos:17.4:r2-s10:*:*:*:*:*:*
juniper junos 17.4 cpe:2.3:o:juniper:junos:17.4:r2-s2:*:*:*:*:*:*
juniper junos 17.4 cpe:2.3:o:juniper:junos:17.4:r2-s3:*:*:*:*:*:*
juniper junos 17.4 cpe:2.3:o:juniper:junos:17.4:r2-s4:*:*:*:*:*:*
juniper junos 17.4 cpe:2.3:o:juniper:junos:17.4:r2-s5:*:*:*:*:*:*
juniper junos 17.4 cpe:2.3:o:juniper:junos:17.4:r2-s6:*:*:*:*:*:*
juniper junos 17.4 cpe:2.3:o:juniper:junos:17.4:r2-s7:*:*:*:*:*:*
juniper junos 17.4 cpe:2.3:o:juniper:junos:17.4:r2-s8:*:*:*:*:*:*
juniper junos 17.4 cpe:2.3:o:juniper:junos:17.4:r2-s9:*:*:*:*:*:*
juniper junos 17.4 cpe:2.3:o:juniper:junos:17.4:r3:*:*:*:*:*:*
juniper junos 17.4 cpe:2.3:o:juniper:junos:17.4:r3-s1:*:*:*:*:*:*
juniper junos 18.2 cpe:2.3:o:juniper:junos:18.2:-:*:*:*:*:*:*
juniper junos 18.2 cpe:2.3:o:juniper:junos:18.2:r1:*:*:*:*:*:*
juniper junos 18.2 cpe:2.3:o:juniper:junos:18.2:r1:-:*:*:*:*:*
juniper junos 18.2 cpe:2.3:o:juniper:junos:18.2:r1-s3:*:*:*:*:*:*
juniper junos 18.2 cpe:2.3:o:juniper:junos:18.2:r1-s4:*:*:*:*:*:*
juniper junos 18.2 cpe:2.3:o:juniper:junos:18.2:r1-s5:*:*:*:*:*:*
juniper junos 18.2 cpe:2.3:o:juniper:junos:18.2:r2:*:*:*:*:*:*
juniper junos 18.2 cpe:2.3:o:juniper:junos:18.2:r2-s1:*:*:*:*:*:*
juniper junos 18.2 cpe:2.3:o:juniper:junos:18.2:r2-s2:*:*:*:*:*:*
juniper junos 18.2 cpe:2.3:o:juniper:junos:18.2:r2-s3:*:*:*:*:*:*
juniper junos 18.2 cpe:2.3:o:juniper:junos:18.2:r2-s4:*:*:*:*:*:*
juniper junos 18.2 cpe:2.3:o:juniper:junos:18.2:r2-s5:*:*:*:*:*:*
juniper junos 18.2 cpe:2.3:o:juniper:junos:18.2:r2-s6:*:*:*:*:*:*
juniper junos 18.2 cpe:2.3:o:juniper:junos:18.2:r3:*:*:*:*:*:*
juniper junos 18.2 cpe:2.3:o:juniper:junos:18.2:r3-s1:*:*:*:*:*:*
juniper junos 18.2 cpe:2.3:o:juniper:junos:18.2:r3-s2:*:*:*:*:*:*
juniper junos 18.2x75 cpe:2.3:o:juniper:junos:18.2x75:-:*:*:*:*:*:*
juniper junos 18.2x75 cpe:2.3:o:juniper:junos:18.2x75:d12:*:*:*:*:*:*
juniper junos 18.2x75 cpe:2.3:o:juniper:junos:18.2x75:d20:*:*:*:*:*:*
juniper junos 18.3 cpe:2.3:o:juniper:junos:18.3:-:*:*:*:*:*:*
juniper junos 18.3 cpe:2.3:o:juniper:junos:18.3:r1:*:*:*:*:*:*
juniper junos 18.3 cpe:2.3:o:juniper:junos:18.3:r1-s1:*:*:*:*:*:*
juniper junos 18.3 cpe:2.3:o:juniper:junos:18.3:r1-s2:*:*:*:*:*:*
juniper junos 18.3 cpe:2.3:o:juniper:junos:18.3:r1-s3:*:*:*:*:*:*
juniper junos 18.3 cpe:2.3:o:juniper:junos:18.3:r1-s5:*:*:*:*:*:*

References for CVE-2020-1665

URL Tags
https://kb.juniper.net/JSA11062 Vendor Advisory
https://kb.juniper.net/KB25385 Vendor Advisory
cvelogic Threat Intelligence