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JunosOperating system · Juniper

CVE-2024-30386

MEDIUM · 5.3 CVSS v3.1 Published 2024-04-12
Fix available
A fix is available. Upgrade to 20.4 or later.
See remediation →
58/100
Remediation priority · Elevated
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
A Use-After-Free vulnerability in the Layer 2 Address Learning Daemon (l2ald) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated, adjacent attacker to cause l2ald to crash leading to a Denial-of-Service (DoS). In an EVPN-VXLAN scenario, when state updates are received and processed by the affected system, the correct order of some processing steps is not ensured, which can lead to an l2ald crash and restart. Whether the crash occurs depends on system internal timing which is outside the attackers control. This issue affects: Junos OS:  * All versions before 20.4R3-S8, * 21.2 versions before 21.2R3-S6, * 21.3 versions before 21.3R3-S5, * 21.4 versions before 21.4R3-S4, * 22.1 versions before 22.1R3-S3, * 22.2 versions before 22.2R3-S1, * 22.3 versions before 22.3R3,, * 22.4 versions before 22.4R2; Junos OS Evolved:  * All versions before 20.4R3-S8-EVO, * 21.2-EVO versions before 21.2R3-S6-EVO,  * 21.3-EVO versions before 21.3R3-S5-EVO, * 21.4-EVO versions before 21.4R3-S4-EVO, * 22.1-EVO versions before 22.1R3-S3-EVO, * 22.2-EVO versions before 22.2R3-S1-EVO, * 22.3-EVO versions before 22.3R3-EVO, * 22.4-EVO versions before 22.4R2-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

Use-After-Free vulnerability in Juniper's Layer 2 Address Learning Daemon (l2ald) allows an unauthenticated adjacent attacker to crash the daemon via a race condition in EVPN-VXLAN state update processing, where incorrect ordering of processing steps leads to a use-after-free and daemon restart.

MitigationUpgrade Junos OS or Junos OS Evolved to the fixed versions specified in the advisory (20.4R3-S8, 21.2R3-S6, 21.3R3-S5, 21.4R3-S4, 22.1R3-S3, 22.2R3-S1, 22.3R3, or 22.4R2 and later).

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= 21.3= 21.4= 22.1= 22.2= 22.3= 22.4
Junos Os EvolvedOperating system
Affected:< 20.4= 20.4= 21.2= 21.3= 21.4= 22.1= 22.2= 22.3= 22.4

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
Adjacent
Complexity
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:A/AC:H/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 installed Junos version
    Run 'show version' or 'request system version' to obtain the exact Junos OS or Junos OS Evolved version number
    Affected if The version matches any of the affected versions listed: < 20.4, = 20.4, = 21.2, = 21.3, = 21.4, = 22.1, = 22.2, = 22.3, = 22.4
  2. Confirm EVPN-VXLAN is configured
    Run 'show configuration protocols evpn' and look for vxlan-related configuration, or check 'show evpn database' to see if EVPN-VXLAN instances exist
    Affected if EVPN-VXLAN is actively configured and operational on the device
  3. Verify l2ald daemon status
    Run 'show system processes daemon l2ald' or check daemon status via 'show system connections' to confirm l2ald is running
    Affected if The l2ald daemon is running and handling Layer 2 address learning for EVPN-VXLAN
  4. Check for recent daemon restarts
    Run 'show log messages' and search for l2ald crash or restart events using 'show log messages | match l2ald'
    Affected if The l2ald daemon has recently crashed or restarted unexpectedly

You are affected if your device runs a vulnerable Junos version AND has EVPN-VXLAN configured, as the race condition only occurs in EVPN-VXLAN state update processing within l2ald.

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

Upgrade Junos OS or Junos OS Evolved to the fixed versions specified in the advisory (20.4R3-S8, 21.2R3-S6, 21.3R3-S5, 21.4R3-S4, 22.1R3-S3, 22.2R3-S1, 22.3R3, or 22.4R2 and later).

Recommended fix High confidence

Upgrade to the fixed release for your version branch (20.4R3-S8, 21.2R3-S6, 21.3R3-S5, 21.4R3-S4, 22.1R3-S3, 22.2R3-S1, 22.3R3, or 22.4R2 for Junos OS; corresponding -EVO versions for Junos OS Evolved)

  1. 1. Identify the current Junos OS or Junos OS Evolved version running on the device using 'show version'
  2. 2. Determine which version branch (20.4, 21.2, 21.3, 21.4, 22.1, 22.2, 22.3, or 22.4) the current installation falls into
  3. 3. For Junos OS: Upgrade to the appropriate fixed version for your branch: 20.4R3-S8, 21.2R3-S6, 21.3R3-S5, 21.4R3-S4, 22.1R3-S3, 22.2R3-S1, 22.3R3, or 22.4R2
  4. 4. For Junos OS Evolved: Upgrade to the appropriate fixed version for your branch: 20.4R3-S8-EVO, 21.2R3-S6-EVO, 21.3R3-S5-EVO, 21.4R3-S4-EVO, 22.1R3-S3-EVO, 22.2R3-S1-EVO, 22.3R3-EVO, or 22.4R2-EVO
  5. 5. Schedule a maintenance window as the upgrade will require a system reboot
  6. 6. Backup current configuration using 'request system configuration rescue save'
  7. 7. Upload the appropriate Junos upgrade package to the device
  8. 8. Perform the upgrade using 'request system software add <package>' and reboot
Caveat Standard Junos upgrade risks apply - ensure configuration compatibility review before upgrading; plan for reboot downtime

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

Fix this in Junos Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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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-2024-30386 in production — separate from our analysis above.

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What this is

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