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JunosOperating system · Juniper

CVE-2020-1653

HIGH · 7.5 CVSS v3.1 Published 2020-07-17
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
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 Junos OS devices, a stream of TCP packets sent to the Routing Engine (RE) may cause mbuf leak which can lead to Flexible PIC Concentrator (FPC) crash or the system to crash and restart (vmcore). This issue can be trigged by IPv4 or IPv6 and it is caused only by TCP packets. This issue is not related to any specific configuration and it affects Junos OS releases starting from 17.4R1. However, this issue does not affect Junos OS releases prior to 18.2R1 when Nonstop active routing (NSR) is configured [edit routing-options nonstop-routing]. The number of mbufs is platform dependent. The following command provides the number of mbufs counter that are currently in use and maximum number of mbufs that can be allocated on a platform: user@host> show system buffers 2437/3143/5580 mbufs in use (current/cache/total) Once the device runs out of mbufs, the FPC crashes or the vmcore occurs and the device might become inaccessible requiring a manual restart. This issue affects Juniper Networks Junos OS 17.4 versions prior to 17.4R2-S11, 17.4R3-S2; 18.1 versions prior to 18.1R3-S10; 18.2 versions prior to 18.2R2-S7, 18.2R3-S5; 18.2X75 versions prior to 18.2X75-D41, 18.2X75-D420.12, 18.2X75-D51, 18.2X75-D60, 18.2X75-D34; 18.3 versions prior to 18.3R2-S4, 18.3R3-S2; 18.4 versions prior to 18.4R1-S7, 18.4R2-S4, 18.4R3-S1; 19.1 versions prior to 19.1R1-S5, 19.1R2-S1, 19.1R3; 19.2 versions prior to 19.2R1-S5, 19.2R2; 19.3 versions prior to 19.3R2-S3, 19.3R3; 19.4 versions prior to 19.4R1-S2, 19.4R2. Versions of Junos OS prior to 17.4R1 are unaffected by this vulnerability.

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

A memory buffer (mbuf) leak in Juniper Junos OS allows crafted TCP packets sent to the Routing Engine to exhaust mbuf resources, causing Flexible PIC Concentrator (FPC) crashes or complete system crashes requiring vmcore restart. The vulnerability is triggered by IPv4 or IPv6 TCP packet streams and affects versions from 17.4R1 through 19.4R2.

MitigationApply the vendor-supplied Junos OS patches (17.4R2-S11, 17.4R3-S2, 18.1R3-S10, 18.2R2-S7, 18.2R3-S5, or later versions per the advisory) after planning appropriate maintenance windows.

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:= 17.4= 18.1= 18.2= 18.2x75= 18.3= 18.4= 19.1= 19.2= 19.3= 19.4

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
High

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

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 Junos OS version
    Run the command 'show version' or 'show version detail' on the device to retrieve the installed Junos OS version
    Affected if The version falls within 17.4R1 through 19.4R2, specifically any of these: 17.4, 18.1, 18.2, 18.2x75, 18.3, 18.4, 19.1, 19.2, 19.3, or 19.4 (or any version between 17.4R1 and 19.4R2 not explicitly listed)
  2. Verify Routing Engine network exposure
    Review the device's interface configuration and firewall policies to determine whether the Routing Engine (via management interface, lo0, or other interfaces) is directly accessible from untrusted networks. Check if services like SSH, Telnet, or other TCP-based management services are listening on interfaces reachable from outside
    Affected if The Routing Engine is directly reachable via IPv4 or IPv6 TCP traffic from untrusted or external networks
  3. Review system crash logs
    Execute 'show system core-dumps' or check /var/crash/ for core files. Review 'show log messages' for FPC crash indications or kernel panics. Use 'request support information' for detailed crash analysis
    Affected if Recent FPC crashes, system crashes, or vmcore dumps are present that correlate with mbuf exhaustion symptoms
  4. Check for mbuf exhaustion indicators
    Run 'show system buffers' or 'show system memory' to inspect buffer utilization. Look for warning messages in system logs regarding mbuf allocation failures
    Affected if Abnormally high mbuf consumption or buffer allocation failures are observed

You are affected if your device runs Junos OS versions 17.4R1 through 19.4R2 and the Routing Engine is accessible via IPv4 or IPv6 TCP traffic from untrusted sources, or if you observe mbuf exhaustion symptoms or FPC crashes consistent with this vulnerability.

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 vendor-supplied Junos OS patches (17.4R2-S11, 17.4R3-S2, 18.1R3-S10, 18.2R2-S7, 18.2R3-S5, or later versions per the advisory) after planning appropriate maintenance windows.

Fix this in Junos Scoped from the published advisory
  • Consultation4.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,690
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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-2020-1653 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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