dbcve.org
Junos Os EvolvedOperating system · Juniper

CVE-2024-21604

HIGH · 7.5 CVSS v3.1 Published 2024-01-12
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
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 Allocation of Resources Without Limits or Throttling vulnerability in the kernel of Juniper Networks Junos OS Evolved allows an unauthenticated, network-based attacker to cause a Denial of Service (DoS). If a high rate of specific valid packets are processed by the routing engine (RE) this will lead to a loss of connectivity of the RE with other components of the chassis and thereby a complete and persistent system outage. Please note that a carefully designed lo0 firewall filter will block or limit these packets which should prevent this issue from occurring. The following log messages can be seen when this issue occurs: <host> kernel: nf_conntrack: nf_conntrack: table full, dropping packet This issue affects Juniper Networks Junos OS Evolved: * All versions earlier than 20.4R3-S7-EVO; * 21.2R1-EVO and later versions; * 21.4-EVO versions earlier than 21.4R3-S5-EVO; * 22.1-EVO versions earlier than 22.1R3-S2-EVO; * 22.2-EVO versions earlier than 22.2R3-EVO; * 22.3-EVO versions earlier than 22.3R2-EVO; * 22.4-EVO versions earlier than 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

A kernel-level resource exhaustion vulnerability in Juniper Networks Junos OS Evolved allows unauthenticated attackers to cause DoS by sending specific valid packets at high rates, filling the nf_conntrack table and causing the routing engine to lose connectivity with chassis components, resulting in complete system outage.

MitigationApply the appropriate Junos OS Evolved software update per the version matrix, or implement a lo0 firewall filter to block or limit the specific packets before they reach the routing engine.

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:= 21.2= 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
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/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. Confirm product is Junos OS Evolved
    Run 'show version' and verify the product name includes 'Junos OS Evolved' (not regular Junos OS)
    Affected if Product is Junos OS Evolved (the vulnerability only affects Evolved version)
  2. Check installed version against affected releases
    Run 'show version' and compare the Junos OS Evolved version to: 21.2, 21.4, 22.1, 22.2, 22.3, or 22.4
    Affected if Version exactly matches one of the listed affected versions
  3. Determine network exposure
    Review interface configurations and access lists to determine if the device is directly reachable from untrusted networks on any external-facing interfaces
    Affected if Device is directly accessible from untrusted networks without upstream filtering
  4. Inspect nf_conntrack table usage
    Run 'show system connections nf_conntrack count' or 'run show jvision nf_conntrack' (if available) to check current connection tracking table utilization
    Affected if Connection tracking table shows unusually high connection counts approaching capacity limits
  5. Review lo0 firewall filter configuration
    Run 'show configuration interfaces lo0' and inspect for firewall filter terms applied to the loopback interface
    Affected if No firewall filter is applied to lo0 interface to limit or block specific packets before they reach the routing engine

User is affected if the device runs Junos OS Evolved version 21.2, 21.4, 22.1, 22.2, 22.3, or 22.4 AND is directly reachable from untrusted networks without protective filters.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the appropriate Junos OS Evolved software update per the version matrix, or implement a lo0 firewall filter to block or limit the specific packets before they reach the routing engine.

Recommended fix High confidence

Upgrade to 20.4R3-S7-EVO, 21.4R3-S5-EVO, 22.1R3-S2-EVO, 22.2R3-EVO, 22.3R2-EVO, or 22.4R2-EVO (depending on your current branch)

  1. 1. Identify the current Junos OS Evolved version running on the device using 'show version' command.
  2. 2. Based on the current version branch, upgrade to one of the fixed releases: 20.4R3-S7-EVO, 21.4R3-S5-EVO, 22.1R3-S2-EVO, 22.2R3-EVO, 22.3R2-EVO, or 22.4R2-EVO.
  3. 3. Schedule a maintenance window as the upgrade will require a system reboot.
  4. 4. Before upgrading, back up the current configuration using 'request system configuration rescue save'.
  5. 5. Download the appropriate fixed Junos OS Evolved image from the Juniper Networks support portal.
  6. 6. Install the upgrade using 'request system software add <path-to-package> reboot'.
  7. 7. Alternatively, as an immediate mitigation pending upgrade, apply a lo0 firewall filter to block or limit the specific packets causing the nf_conntrack table overflow. Configure filters on the lo0 interface following Juniper best practices for control plane protection.
Caveat Standard Junos OS upgrade considerations apply - review release notes for compatibility and ensure configuration compatibility before upgrading

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

Fix this in Junos Os Evolved Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,130
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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-2024-21604 in production — separate from our analysis above.

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What this is

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What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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  • No spam, self-promotion, credentials, or personal data