CVE-2024-39520
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 · uneditedAn Improper Neutralization of Special Elements vulnerability in Juniper Networks Junos OS Evolved commands allows a local, authenticated attacker with low privileges to escalate their privileges to 'root' leading to a full compromise of the system. The Junos OS Evolved CLI doesn't properly handle command options in some cases, allowing users which execute specific CLI commands with a crafted set of parameters to escalate their privileges to root on shell level. This issue affects Junos OS Evolved: * All version before 20.4R3-S6-EVO, * 21.2-EVO versions before 21.2R3-S4-EVO, * 21.4-EVO versions before 21.4R3-S6-EVO, * 22.2-EVO versions before 22.2R2-S1-EVO, 22.2R3-EVO, * 22.3-EVO versions before 22.3R2-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 confidenceA local privilege escalation vulnerability exists in Juniper Networks Junos OS Evolved CLI where improper handling of special elements in command options allows authenticated low-privilege users to execute crafted CLI commands that spawn a root shell, achieving full system compromise.
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< 20.4= 20.4= 21.2= 21.4= 22.2= 22.3CVSS 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 checksWork through these to decide whether this CVE applies to you.
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Identify Junos OS Evolved versionRun 'show version' or 'show version details' in the CLI to obtain the installed Junos OS Evolved version numberAffected if The displayed version matches any of the affected versions: < 20.4, 20.4, 21.2, 21.4, 22.2, or 22.3
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Confirm product is Junos OS EvolvedVerify the system is running Junos OS Evolved (not classic Junos OS) by checking the output from 'show version' for 'Junos OS Evolved' or 'EVO' in the product nameAffected if The product is Junos OS Evolved and the version falls within the affected ranges listed above
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Verify low-privilege CLI access existsCheck if non-root user accounts have CLI access by reviewing user accounts configured with 'class operator', 'class read-only', or similar non-root privilege levels using 'show system login'Affected if Low-privilege authenticated users have CLI access to the system
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Inspect for unexpected root shellsCheck for any processes running as root that resemble shell sessions (such as /bin/sh, /bin/bash spawned from CLI) using 'show system processes' or by reviewing system logs for suspicious shell spawn eventsAffected if Root shells or unexpected privileged processes are found that were not initiated by authorized administrators
The environment is affected if the system runs Junos OS Evolved with a version matching < 20.4, 20.4, 21.2, 21.4, 22.2, or 22.3 and low-privilege users have CLI access.
Generated from the published advisory. Verify against your own configuration.
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 · scoped20.4
Apply the vendor-supplied patches by upgrading Junos OS Evolved to the fixed versions (20.4R3-S6-EVO, 21.2R3-S4-EVO, 21.4R3-S6-EVO, 22.2R2-S1-EVO/22.2R3-EVO, or 22.3R2-EVO or later) as specified in the Juniper advisory.
20.4R3-S6-EVO or 21.2R3-S4-EVO or 21.4R3-S6-EVO or 22.2R2-S1-EVO/22.2R3-EVO or 22.3R2-EVO (depending on current branch)
- 1. Identify the current Junos OS Evolved version running on the device using 'show version'
- 2. Access Juniper Networks support portal (supportportal.juniper.net) and download the appropriate fixed EVO image for your platform
- 3. Verify the integrity of the downloaded package using checksums provided on the support portal
- 4. Upload the fixed software package to the device using 'request system software add' or equivalent file transfer method
- 5. Run 'request system software validate' to check compatibility before installation (if available)
- 6. Initiate the software installation using 'request system software add <package> reboot'
- 7. After reboot, confirm the new version is installed using 'show version'
- 8. Verify the fix is applied by ensuring the version matches or exceeds the fixed release (20.4R3-S6-EVO, 21.2R3-S4-EVO, 21.4R3-S6-EVO, 22.2R2-S1-EVO, 22.2R3-EVO, or 22.3R2-EVO)
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation4.0 h
- Testing4.0 h
- Review / QA2.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2024-39520 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2024-39520 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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