dbcve.org
JunosOperating system · Juniper

CVE-2021-0246

HIGH · 7.3 CVSS v3.1 Published 2021-04-22
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
75/100
Remediation priority · High
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 SRX1500, SRX4100, SRX4200, SRX4600, SRX5000 Series with SPC2/SPC3, devices using tenant services on Juniper Networks Junos OS, due to incorrect default permissions assigned to tenant system administrators a tenant system administrator may inadvertently send their network traffic to one or more tenants while concurrently modifying the overall device system traffic management, affecting all tenants and the service provider. Further, a tenant may inadvertently receive traffic from another tenant. This issue affects: Juniper Networks Junos OS 18.3 version 18.3R1 and later versions on SRX1500, SRX4100, SRX4200, SRX4600, SRX5000 Series with SPC2; 18.3 versions prior to 18.3R3 on SRX1500, SRX4100, SRX4200, SRX4600, SRX5000 Series with SPC2; 18.4 versions prior to 18.4R2 on SRX1500, SRX4100, SRX4200, SRX4600, SRX5000 Series with SPC2/SPC3; 19.1 versions prior to 19.1R2 on SRX1500, SRX4100, SRX4200, SRX4600, SRX5000 Series with SPC2/SPC3. This issue does not affect: Juniper Networks Junos OS versions prior to 18.3R1.

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

This is a tenant isolation vulnerability in Junos OS SRX series devices (SRX1500, SRX4100, SRX4200, SRX4600, SRX5000) with SPC2/SPC3 cards. Incorrect default permissions assigned to tenant system administrators allow them to inadvertently send network traffic to other tenants while modifying overall device system traffic management, breaking tenant isolation and potentially exposing traffic between tenants.

MitigationUpgrade Junos OS to version 18.3R3, 18.4R2, 19.1R2 or later (depending on the current branch) to receive the corrected default permissions for tenant system administrators. Verify tenant isolation after upgrade.

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:= 18.3= 18.4= 19.1

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
Local
Complexity
Low
Privileges
High
User interaction
None
Scope
Changed
Confidentiality
Low
Integrity
High
Availability
Low

CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:L/I:H/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 the SRX device model
    Run 'show system information' or 'show chassis hardware' to confirm the device is an SRX1500, SRX4100, SRX4200, SRX4600, or SRX5000
    Affected if Device model is one of these affected SRX series models
  2. Verify SPC2 or SPC3 card presence
    Run 'show chassis hardware' or 'show chassis fpc' to identify installed SPC cards
    Affected if SPC2 or SPC3 cards are installed in the device
  3. Check installed Junos OS version
    Run 'show version' to obtain the exact Junos OS version number
    Affected if Version is 18.3 (any release), 18.4 (any release), or 19.1 (any release)
  4. Identify tenant system administrators
    Run 'show system login' or 'show configuration system login' to list all configured login accounts and their classes, particularly looking for accounts assigned to tenant administration roles
    Affected if Tenant system administrator accounts exist with elevated permissions that could affect system-wide traffic management
  5. Verify tenant isolation configuration
    Run 'show logical-systems' or 'show configuration logical-systems' to review tenant logical system definitions and their traffic separation settings
    Affected if Multiple logical systems or tenant systems are configured without proper isolation controls between them

Device is affected if it is an SRX1500/4100/4200/4600/5000 with SPC2/SPC3 cards running Junos OS version 18.3, 18.4, or 19.1 and has tenant system administrators 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

Upgrade Junos OS to version 18.3R3, 18.4R2, 19.1R2 or later (depending on the current branch) to receive the corrected default permissions for tenant system administrators. Verify tenant isolation after upgrade.

Fix this in Junos Scoped from the published advisory
  • Consultation4.0 h
  • Implementation6.0 h
  • Testing6.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,140
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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-2021-0246 in production — separate from our analysis above.

No notes yet

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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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