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JunosOperating system · Juniper

CVE-2018-0031

MEDIUM · 5.9 CVSS v3.0 Published 2018-07-11
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
68/100
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
Receipt of specially crafted UDP/IP packets over MPLS may be able to bypass a stateless firewall filter. The crafted UDP packets must be encapsulated and meet a very specific packet format to be classified in a way that bypasses IP firewall filter rules. The packets themselves do not cause a service interruption (e.g. RPD crash), but receipt of a high rate of UDP packets may be able to contribute to a denial of service attack. This issue only affects processing of transit UDP/IP packets over MPLS, received on an interface with MPLS enabled. TCP packet processing and non-MPLS encapsulated UDP packet processing are unaffected by this issue. Affected releases are Juniper Networks Junos OS: 12.1X46 versions prior to 12.1X46-D76; 12.3 versions prior to 12.3R12-S10; 12.3X48 versions prior to 12.3X48-D66, 12.3X48-D70; 14.1X53 versions prior to 14.1X53-D47; 15.1 versions prior to 15.1F6-S10, 15.1R4-S9, 15.1R6-S6, 15.1R7; 15.1X49 versions prior to 15.1X49-D131, 15.1X49-D140; 15.1X53 versions prior to 15.1X53-D59 on EX2300/EX3400; 15.1X53 versions prior to 15.1X53-D67 on QFX10K; 15.1X53 versions prior to 15.1X53-D233 on QFX5200/QFX5110; 15.1X53 versions prior to 15.1X53-D471, 15.1X53-D490 on NFX; 16.1 versions prior to 16.1R3-S8, 16.1R4-S9, 16.1R5-S4, 16.1R6-S3, 16.1R7; 16.2 versions prior to 16.2R1-S6, 16.2R2-S5, 16.2R3; 17.1 versions prior to 17.1R1-S7, 17.1R2-S7, 17.1R3; 17.2 versions prior to 17.2R1-S6, 17.2R2-S4, 17.2R3; 17.2X75 versions prior to 17.2X75-D100; 17.3 versions prior to 17.3R1-S4, 17.3R2-S2, 17.3R3; 17.4 versions prior to 17.4R1-S3, 17.4R2; 18.1 versions prior to 18.1R2; 18.2X75 versions prior to 18.2X75-D5.

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 stateless firewall filter bypass vulnerability exists in Junos OS where specially crafted UDP/IP packets encapsulated over MPLS can evade IP firewall filter rules. The packets must meet a very specific format to be misclassified, allowing them to bypass filtering. Only transit UDP/IP packets received on MPLS-enabled interfaces are affected; TCP and non-MPLS UDP traffic are unaffected. While the packets don't directly crash services, high-volume receipt can contribute to denial of service.

MitigationApply the appropriate Junos OS update from the vendor (12.1X46-D76, 12.3R12-S10, 12.3X48-D66/D70, 14.1X53-D47, 15.1F6-S10/15.1R4-S9/15.1R6-S6/15.1R7, 15.1X49-D131/D140, 16.1R3-S8/16.1R4-S9/16.1R5-S4/16.1R6-S3/16.1R7, or later). As a temporary measure, review and restrict MPLS-enabled interfaces or implement additional filtering on upstream devices.

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:= 12.1x46= 12.3= 12.3x48= 14.1x53= 15.1= 15.1x49= 15.1x53= 16.1= 16.2= 17.1= 17.2= 17.2x75

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

CVSS:3.0/AV:N/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. Check Junos OS version
    Run 'show version' command and note the installed Junos OS version
    Affected if The installed version matches any of these affected versions: 12.1x46, 12.3, 12.3x48, 14.1x53, 15.1, 15.1x49, 15.1x53, 16.1, 16.2, 17.1, 17.2, or 17.2x75
  2. Identify MPLS-enabled interfaces
    Run 'show configuration protocols mpls' and 'show interfaces | match mpls' to list interfaces with MPLS protocol enabled
    Affected if Any interface has MPLS protocol configured and is actively receiving transit traffic
  3. Verify UDP firewall filter rules exist
    Run 'show configuration firewall' and look for filter terms applied to UDP traffic, or run 'show firewall' to list configured filter sets
    Affected if Firewall filters are configured to filter UDP traffic on the affected device
  4. Confirm filter application to MPLS interfaces
    Run 'show configuration interfaces <mpls-interface> unit <unit> family inet filter' to check if firewall filters are applied to MPLS-enabled interfaces
    Affected if Firewall filters are applied to MPLS-enabled interfaces receiving transit UDP/IP packets

The device is affected if it runs a vulnerable Junos OS version (listed above), has MPLS-enabled interfaces receiving transit UDP/IP traffic, AND has IP firewall filters applied that are expected to block or filter that UDP traffic but may be bypassed.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the appropriate Junos OS update from the vendor (12.1X46-D76, 12.3R12-S10, 12.3X48-D66/D70, 14.1X53-D47, 15.1F6-S10/15.1R4-S9/15.1R6-S6/15.1R7, 15.1X49-D131/D140, 16.1R3-S8/16.1R4-S9/16.1R5-S4/16.1R6-S3/16.1R7, or later). As a temporary measure, review and restrict MPLS-enabled interfaces or implement additional filtering on upstream devices.

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-2018-0031 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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