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JunosOperating system · Juniper

CVE-2023-36848

MEDIUM · 6.5 CVSS v3.1 Published 2023-07-14
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
70/100
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
An Improper Handling of Undefined Values vulnerability in the periodic packet management daemon (PPMD) of Juniper Networks Junos OS on MX Series(except MPC10, MPC11 and LC9600) allows an unauthenticated adjacent attacker to cause a Denial of Service (DoS). When a malformed CFM packet is received, it leads to an FPC crash. Continued receipt of these packets causes a sustained denial of service. This vulnerability occurs only when CFM has been configured on the interface. This issue affects Juniper Networks Junos OS: versions prior to 19.1R3-S10 on MX Series; 19.2 versions prior to 19.2R3-S7 on MX Series; 19.3 versions prior to 19.3R3-S8 on MX Series; 19.4 versions prior to 19.4R3-S12 on MX Series; 20.1 version 20.1R1 and later versions on MX Series; 20.2 versions prior to 20.2R3-S8 on MX Series; 20.3 version 20.3R1 and later versions on MX Series; 20.4 versions prior to 20.4R3-S7 on MX Series; 21.1 versions prior to 21.1R3-S5 on MX Series; 21.2 versions prior to 21.2R3-S5 on MX Series; 21.3 versions prior to 21.3R3-S4 on MX Series; 21.4 versions prior to 21.4R3-S4 on MX Series; 22.1 versions prior to 22.1R3-S3 on MX Series; 22.2 versions prior to 22.2R3-S1 on MX Series; 22.3 versions prior to 22.3R3 on MX Series; 22.4 versions prior to 22.4R1-S2, 22.4R2 on MX Series.

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

An Improper Handling of Undefined Values vulnerability in the periodic packet management daemon (PPMD) of Juniper Networks Junos OS on MX Series allows an unauthenticated adjacent attacker to cause FPC crashes by sending malformed CFM (Connectivity Fault Management) packets. This triggers a denial of service that becomes sustained with continued receipt of these packets, but only affects interfaces where CFM has been configured.

MitigationApply the appropriate Junos OS upgrade to a fixed version as specified in the Juniper advisory; if immediate patching is not possible, consider disabling CFM on affected interfaces or implementing network segmentation to limit adjacent attack surface.

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:= 19.1= 19.2= 19.3= 19.4= 20.1= 20.2= 20.3= 20.4= 21.1= 21.2= 21.3= 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
Adjacent
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:A/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 MX Series hardware
    Run 'show chassis hardware' or 'show version' to identify the device model
    Affected if Device is NOT an MX Series router (vulnerability only affects MX Series)
  2. Check Junos OS version
    Run 'show version' and compare the installed Junos version to the affected range: 19.1, 19.2, 19.3, 19.4, 20.1, 20.2, 20.3, 20.4, 21.1, 21.2, 21.3, 21.4
    Affected if Installed version matches one of the affected versions listed
  3. Verify CFM configuration
    Run 'show configuration | match cfm' or 'show protocols oam' to identify if Connectivity Fault Management is configured on any interfaces
    Affected if CFM is actively configured on any interfaces - the vulnerability only triggers on interfaces where CFM has been configured
  4. Confirm PPMD daemon is running
    Run 'show system processes' or 'show system processes | match ppmd' to verify the periodic packet management daemon is active
    Affected if PPMD daemon is running and CFM is configured - both conditions must be true for the vulnerability to be exploitable

Device is affected if it is an MX Series running Junos 19.1-21.4 with CFM configured on at least one interface and the PPMD daemon is active.

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 upgrade to a fixed version as specified in the Juniper advisory; if immediate patching is not possible, consider disabling CFM on affected interfaces or implementing network segmentation to limit adjacent attack surface.

Recommended fix High confidence

For 19.1: upgrade to 19.1R3-S10 or later; For 19.2: upgrade to 19.2R3-S7 or later; For 19.3: upgrade to 19.3R3-S8 or later; For 19.4: upgrade to 19.4R3-S12 or later; For 20.2: upgrade to 20.2R3-S8 or later; For 20.4: upgrade to 20.4R3-S7 or later; For 21.1: upgrade to 21.1R3-S5 or later; For 21.2: u

  1. 1. Identify the current Junos OS version on the MX Series device using 'show version'
  2. 2. Determine if CFM (Connectivity Fault Management) is configured on any interface using 'show configuration protocols oam' or 'show configuration protocols cfm'
  3. 3. If CFM is not required, consider disabling it to mitigate the vulnerability
  4. 4. If CFM is required, plan for a software upgrade to a fixed release
  5. 5. Schedule a maintenance window for the upgrade
  6. 6. Download the appropriate fixed Junos OS version from Juniper Networks support portal
  7. 7. Follow standard Junos OS upgrade procedures: copy the image to the device, verify checksum, initiate upgrade with 'request system software add <package> reboot'
  8. 8. After upgrade, verify the new version is running with 'show version'
Caveat Standard Junos OS upgrade considerations apply - review release notes for any configuration changes or compatibility notices, and test in lab environment before production deployment

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
  • Testing8.0 h
  • Review / QA4.0 h
24.0 hours of engineering $4,160
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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-2023-36848 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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