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JunosOperating system · Juniper

CVE-2024-39511

MEDIUM · 5.5 CVSS v3.1 Published 2024-07-10
Fix available
A fix is available. Upgrade to 20.4 or later.
See remediation →
57/100
Remediation priority · Elevated
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 Improper Input Validation vulnerability in the 802.1X Authentication (dot1x) Daemon of Juniper Networks Junos OS allows a local, low-privileged attacker with access to the CLI to cause a Denial of Service (DoS). On running a specific operational dot1x command, the dot1x daemon crashes. An attacker can cause a sustained DoS condition by running this command repeatedly. When the crash occurs, the authentication status of any 802.1x clients is cleared, and any authorized dot1x port becomes unauthorized. The client cannot re-authenticate until the dot1x daemon restarts. This issue affects Junos OS: * All versions before 20.4R3-S10; * 21.2 versions before 21.2R3-S7; * 21.4 versions before 21.4R3-S6; * 22.1 versions before 22.1R3-S5; * 22.2 versions before 22.2R3-S3; * 22.3 versions before 22.3R3-S2; * 22.4 versions before 22.4R3-S1; * 23.2 versions before 23.2R2.

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, low-privileged attacker with CLI access can trigger a denial of service in the Junos OS dot1x daemon by executing a specific operational command. The command causes the daemon to crash, which clears 802.1X client authentication states and renders authorized ports unauthorized until the daemon restarts, enabling sustained DoS through repeated command execution.

MitigationApply the appropriate Junos OS software update for your version branch as specified in the Juniper advisory, and schedule a maintenance window to minimize disruption to 802.1X authenticated clients.

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:< 20.4= 20.4= 21.2= 21.4= 22.1= 22.2= 22.3= 22.4= 23.2

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
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/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. Check installed Junos OS version
    Execute 'show version' or 'show version detail' from the CLI and locate the Junos OS version string (e.g., 22.3R3).
    Affected if The installed version matches any of these: versions below 20.4, 20.4, 21.2, 21.4, 22.1, 22.2, 22.3, 22.4, or 23.2.
  2. Verify dot1x daemon is running
    Execute 'show dot1x interface' or 'show dot1x summary' from the CLI to check if 802.1X authentication is configured and the dot1x daemon is active.
    Affected if The dot1x daemon is running and 802.1X authentication is enabled on any interface.
  3. Confirm CLI access exists for low-privileged users
    Review user accounts and their privilege levels using 'show system login' and check the assigned class for each user. Verify if users with 'operator' or 'read-only' class exist.
    Affected if Any low-privileged user account (operator, read-only, or similar restricted class) has CLI access to the device.
  4. Identify exposed dot1x operational commands
    Execute 'request dot1x' commands available to your privilege level and observe if any cause unexpected daemon behavior or errors. Compare available commands against those documented in Juniper's CLI guide for dot1x.
    Affected if A specific operational command executable by a low-privileged user triggers dot1x daemon instability or crash.

You are affected if your Junos version matches the affected list, dot1x authentication is enabled, and a low-privileged user can execute the triggering command via CLI.

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 appropriate Junos OS software update for your version branch as specified in the Juniper advisory, and schedule a maintenance window to minimize disruption to 802.1X authenticated clients.

Recommended fix High confidence

Upgrade to the appropriate fixed release for your branch: 20.4R3-S10, 21.2R3-S7, 21.4R3-S6, 22.1R3-S5, 22.2R3-S3, 22.3R3-S2, 22.4R3-S1, or 23.2R2 (or later)

  1. 1. Identify the current Junos OS version and branch running on the device using `show version`
  2. 2. Determine which branch (20.4, 21.2, 21.4, 22.1, 22.2, 22.3, 22.4, or 23.2) the device is on
  3. 3. For devices on the 20.4 branch, upgrade to 20.4R3-S10 or later
  4. 4. For devices on the 21.2 branch, upgrade to 21.2R3-S7 or later
  5. 5. For devices on the 21.4 branch, upgrade to 21.4R3-S6 or later
  6. 6. For devices on the 22.1 branch, upgrade to 22.1R3-S5 or later
  7. 7. For devices on the 22.2 branch, upgrade to 22.2R3-S3 or later
  8. 8. For devices on the 22.3 branch, upgrade to 22.3R3-S2 or later
Caveat Review Junos OS upgrade documentation for compatibility considerations; some branches may have hardware requirements or feature changes

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

Fix this in Junos Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
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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-2024-39511 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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