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Junos Os EvolvedOperating system · Juniper

CVE-2023-28966

HIGH · 7.8 CVSS v3.1 Published 2023-04-17
Fix available
A fix is available. Upgrade to 20.4 or later.
See remediation →
80/100
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
An Incorrect Default Permissions vulnerability in Juniper Networks Junos OS Evolved allows a low-privileged local attacker with shell access to modify existing files or execute commands as root. The issue is caused by improper file and directory permissions on certain system files, allowing an attacker with access to these files and folders to inject CLI commands as root. This issue affects Juniper Networks Junos OS Evolved: All versions prior to 20.4R3-S5-EVO; 21.2 versions prior to 21.2R3-EVO; 21.3 versions prior to 21.3R2-EVO.

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 local privilege escalation vulnerability exists in Juniper Networks Junos OS Evolved where improper default file and directory permissions on certain system files allow a low-privileged attacker with shell access to modify files or inject CLI commands as root.

MitigationApply the vendor-supplied patches by upgrading Junos OS Evolved to version 20.4R3-S5-EVO, 21.2R3-EVO, 21.3R2-EVO or later per the version branch in use.

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
Junos Os EvolvedOperating system
Affected:< 20.4= 20.4= 21.2= 21.3

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

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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. Check the Junos OS Evolved version
    Run 'show version' or 'cat /etc/version' in the CLI or shell to obtain the installed version
    Affected if The version is < 20.4, = 20.4, = 21.2, or = 21.3
  2. Verify low-privileged shell access exists
    Confirm a non-root user has shell access to the system
    Affected if A low-privileged user can access the shell and read/write to certain system directories
  3. Inspect file permissions on system files
    Run 'ls -la' on critical system directories and files in /opt or /var and check for world-writable or group-writable permissions
    Affected if System files or directories have overly permissive settings (such as world-writable or insecure group ownership) that allow modification by non-root users
  4. Check for command injection vectors
    Verify if low-privileged users can modify configuration files or scripts that are executed with elevated privileges
    Affected if Writable system files are executed by root processes or the CLI

A user is affected if they are running Junos OS Evolved version 20.4, 21.2, or 21.3 (or any version below 20.4) and low-privileged users have shell access to system files with improper permissions.

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.

dbcve · scoped
Upgrade available Upgrade to 20.4 or later
Fixed in 20.4
Interim mitigation

Apply the vendor-supplied patches by upgrading Junos OS Evolved to version 20.4R3-S5-EVO, 21.2R3-EVO, 21.3R2-EVO or later per the version branch in use.

Recommended fix High confidence

20.4R3-S5-EVO or later (for older branches); 21.2R3-EVO or later (for 21.2 branch); 21.3R2-EVO or later (for 21.3 branch)

  1. 1. Identify the current Junos OS Evolved version using the command: show version
  2. 2. Based on the current version, plan the upgrade path: for versions < 20.4 or = 20.4, upgrade to 20.4R3-S5-EVO or later; for = 21.2, upgrade to 21.2R3-EVO or later; for = 21.3, upgrade to 21.3R2-EVO or later
  3. 3. Download the appropriate upgrade image from the Juniper Networks support portal (supportportal.juniper.net)
  4. 4. Transfer the upgrade image to the device using SCP or USB
  5. 5. Initiate the software installation using: request system software add <path-to-image> reboot
  6. 6. After the device reboots, verify the new version using: show version
  7. 7. Confirm the fix is applied by verifying the version is >= 20.4R3-S5-EVO, >= 21.2R3-EVO, or >= 21.3R2-EVO depending on your branch
Caveat Standard Junos OS Evolved upgrade precautions apply - ensure configuration backup and plan for brief downtime

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Junos Os Evolved Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
Get the upgrade done

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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-2023-28966 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data