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JunosOperating system · Juniper

CVE-2020-1665

MEDIUM · 5.3 CVSS v3.1 Published 2020-10-16
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
62/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

On Juniper MX Series and EX9200 Series routers with Trio-based Packet Forwarding Engines, the IPv6 Distributed Denial of Service (DDoS) protection mechanism fails to activate when traffic reaches the configured threshold under certain conditions. This allows the Routing Engine (RE) and/or Flexible PIC Concentrator (FPC) to become overwhelmed, disrupting network protocol operations and interrupting traffic. IPv4 DDoS protection is not affected.

MitigationApply the appropriate Junos OS software update from Juniper Networks (versions specified in the advisory: 17.2R3-S4+, 17.2X75-D102/D110+, 17.3R3-S8+, 17.4R2-S11/17.4R3-S2+, 18.2R2-S7/18.2R3/18.2R3-S3+, 18.2X75-D30+, or 18.3R2-S4/18.3R3-S2+) to remediate the IPv6 DDoS protection bypass.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
JunosOperating system
Affected:= 17.2= 17.2x75= 17.3= 17.4= 18.2= 18.2x75= 18.3

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify device model
    Run 'show chassis hardware' or 'show version' to confirm the device is a Juniper MX Series or EX9200 Series router
    Affected if Device is not MX Series or EX9200 - these are the only affected platforms listed
  2. Check Junos software version
    Run 'show version' to obtain the installed Junos version
    Affected if Version matches any of the affected releases: 17.2, 17.2x75, 17.3, 17.4, 18.2, 18.2x75, or 18.3 (exact versions as listed in the advisory)
  3. Confirm Trio-based Packet Forwarding Engine
    Run 'show chassis pic' or check the hardware inventory for Trio-based PFE - MX Series typically use Trio chipsets
    Affected if PFE is Trio-based - the vulnerability applies specifically to Trio-based PFEs; non-Trio platforms are not affected
  4. Verify IPv6 DDoS protection configuration
    Run 'show ddos-protection protocols' to inspect IPv6 DDoS protection status and configured thresholds
    Affected if IPv6 DDoS protection is configured but fails to activate when traffic reaches threshold - this is the bypass condition
  5. Monitor for IPv6 traffic-induced RE/FPC overload
    Run 'show system processes' and 'show chassis fpc' to check for RE or FPC resource exhaustion correlating with high IPv6 traffic
    Affected if RE or FPC becomes overwhelmed during IPv6 traffic spikes while IPv4 traffic does not cause similar issues - indicating the IPv6 DDoS protection is not activating properly

A user is affected if they have an MX Series or EX9200 router with Trio-based PFE running any of the listed Junos versions (17.2 through 18.3) and observe RE or FPC overload during IPv6 traffic bursts despite having IPv6 DDoS protection configured.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the appropriate Junos OS software update from Juniper Networks (versions specified in the advisory: 17.2R3-S4+, 17.2X75-D102/D110+, 17.3R3-S8+, 17.4R2-S11/17.4R3-S2+, 18.2R2-S7/18.2R3/18.2R3-S3+, 18.2X75-D30+, or 18.3R2-S4/18.3R3-S2+) to remediate the IPv6 DDoS protection bypass.

Fix this in Junos Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,130
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2020-1665 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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