Junos OS: MX series/EX9200 Series: IPv6 DDoS protection does not work as expected.

Description

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.

Scores

EPSS (exploitation in 30 days)

1.3% · top 30% of all CVEs (6 Nov 2026)

The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.3.

Weakness

• CWE-794: Incomplete Filtering of Multiple Instances of Special Elements (opens in a new tab)All about CWE-794 and its CVEs

Affected products

• Juniper Networks · Junos OS

  • affected 17.2 – < 17.2R3-S4
  • affected 17.2X75 – < 17.2X75-D102, 17.2X75-D110
  • affected 17.3 – < 17.3R3-S8
  • affected 17.4 – < 17.4R2-S11, 17.4R3-S2
  • affected 18.2 – < 18.2R2-S7, 18.2R3, 18.2R3-S3
  • affected 18.2X75 – < 18.2X75-D30
  • affected 18.3 – < 18.3R2-S4, 18.3R3-S2

What to do

Solution: The following software releases have been updated to resolve this specific issue: Junos OS 17.2R3-S4, 17.2X75-D102, 17.2X75-D110, 17.3R3-S8, 17.4R2-S11, 17.4R3-S2, 18.2R2-S7, 18.2R3, 18.2R3-S3, 18.2X75-D30, 18.3R2-S4, 18.3R3-S2, 18.4R1, and all subsequent releases.

Workaround: There are no viable workarounds for this issue.

Exploitation: Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

References (2)

• https://kb.juniper.net/JSA11062 (opens in a new tab)x_refsource_CONFIRMx_transferred
• https://kb.juniper.net/KB25385 (opens in a new tab)x_refsource_MISCx_transferred

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2020-1665](https://trackcve.app/badge/CVE-2020-1665.svg)](https://trackcve.app/cve/CVE-2020-1665)

Record last updated 16 Sept 2024, 18:29 UTC.