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JunosOperating system · Juniper

CVE-2024-30410

MEDIUM · 5.8 CVSS v3.1 Published 2024-04-12
Fix available
A fix is available. Upgrade to 20.4 or later.
See remediation →
67/100
Remediation priority · Elevated
Remotely reachable 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
An Incorrect Behavior Order in the routing engine (RE) of Juniper Networks Junos OS on EX4300 Series allows traffic intended to the device to reach the RE instead of being discarded when the discard term is set in loopback (lo0) interface. The intended function is that the lo0 firewall filter takes precedence over the revenue interface firewall filter.  This issue affects only IPv6 firewall filter. This issue only affects the EX4300 switch. No other products or platforms are affected by this vulnerability.  This issue affects Juniper Networks Junos OS: * All versions before 20.4R3-S10, * from 21.2 before 21.2R3-S7, * from 21.4 before 21.4R3-S6.

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

On Juniper EX4300 switches, an incorrect behavior order in the routing engine causes IPv6 traffic intended for the device (to the RE) to reach the routing engine instead of being discarded, even when a discard term is configured in the loopback (lo0) interface firewall filter. The lo0 firewall filter should take precedence over revenue interface firewall filters but fails to do so, allowing unauthorized traffic to reach the RE.

MitigationUpgrade Junos OS to version 20.4R3-S10, 21.2R3-S7, or 21.4R3-S6 or later. Until upgrade, consider additional IPv6 access controls at upstream network segments.

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

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
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N

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 device model
    Run 'show chassis hardware' or 'show version' to confirm the device is an EX4300 switch
    Affected if Device is not an EX4300 switch (different models may have different behaviors)
  2. Check Junos OS version
    Run 'show version' and compare the installed Junos version against the affected ranges: < 20.4, = 20.4, = 21.2, = 21.4
    Affected if Version matches one of the affected versions listed in the CVE
  3. Verify loopback firewall filter configuration
    Run 'show configuration interfaces lo0 unit 0 family inet6 filter' to check if a firewall filter is applied to lo0
    Affected if A firewall filter with an IPv6 discard term exists on lo0 but traffic still reaches the RE (vulnerable condition)
  4. Check for IPv6 firewall filters on revenue interfaces
    Run 'show configuration interfaces' and look for firewall filters applied to revenue ports with family inet6
    Affected if IPv6 firewall filters are configured on revenue interfaces that may process traffic before the lo0 filter takes effect

Device is affected if it is an EX4300 running a vulnerable Junos version (< 20.4, 20.4, 21.2, or 21.4) and has a lo0 firewall filter with an IPv6 discard term that is not properly blocking traffic to the routing engine.

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 to version 20.4R3-S10, 21.2R3-S7, or 21.4R3-S6 or later. Until upgrade, consider additional IPv6 access controls at upstream network segments.

Recommended fix High confidence

20.4R3-S10, 21.2R3-S7, or 21.4R3-S6 (depending on starting version)

  1. Identify the current Junos OS version running on the EX4300 switch using 'show version'
  2. Determine which upgrade path applies based on current version (if <20.4 go to 20.4R3-S10, if 21.2.x go to 21.2R3-S7, if 21.4.x go to 21.4R3-S6)
  3. Download the appropriate Junos OS upgrade package from Juniper Networks support portal
  4. Transfer the upgrade package to the EX4300 device
  5. Initiate the upgrade using 'request system software add <package> reboot' command
  6. Verify the upgrade completed successfully and the new version is running
  7. After upgrade, verify the IPv6 loopback firewall filter now takes precedence over revenue interface filters

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

Fix this in Junos Scoped from the published advisory
  • Consultation4.0 h
  • Implementation3.0 h
  • Testing3.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,150
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Scan for this in your stack

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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-2024-30410 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