CVE-2017-2340
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 · uneditedOn Juniper Networks Junos OS 15.1 releases from 15.1R3 to 15.1R4, 16.1 prior to 16.1R3, on M/MX platforms where Enhanced Subscriber Management for DHCPv6 subscribers is configured, a vulnerability in processing IPv6 ND packets originating from subscribers and destined to M/MX series routers can result in a PFE (Packet Forwarding Engine) hang or crash.
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 confidenceA vulnerability in Junos OS 15.1R3-R4 and 16.1 before 16.1R3 on M/MX platforms allows specially crafted IPv6 Neighbor Discovery packets from DHCPv6 subscribers to cause a Packet Forwarding Engine (PFE) hang or crash when Enhanced Subscriber Management is configured.
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= 15.1= 16.1CVSS 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
- Low
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
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 checksWork through these to decide whether this CVE applies to you.
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Determine Junos OS versionRun 'show version' or 'show version detail' command to identify the installed Junos OS versionAffected if Version is 15.1R3, 15.1R4, or any 16.1 release prior to 16.1R3 (for example, 16.1, 16.1R1, 16.1R2)
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Identify hardware platformRun 'show chassis hardware' or 'show system information' to confirm the device is an M Series router or MX Series routerAffected if Platform is M Series or MX Series
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Verify Enhanced Subscriber Management configurationRun 'show configuration subsystem subsystem-id' or 'show configuration | match enhanced-subscriber-management' to check if Enhanced Subscriber Management is enabledAffected if Enhanced Subscriber Management is configured and active
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Check for DHCPv6 subscriber servicesRun 'show subscribers summary' or 'show configuration services subscriber-management' to identify if DHCPv6 subscriber management is in useAffected if DHCPv6 subscribers are being managed on the device
Device is affected if it runs Junos OS version 15.1R3 through 15.1R4 or 16.1 before 16.1R3, is an M or MX platform, has Enhanced Subscriber Management configured, and processes DHCPv6 subscriber traffic with IPv6 Neighbor Discovery packets.
Generated from the published advisory. Verify against your own configuration.
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 dataUpgrade Junos OS to version 15.1R5 or later, or 16.1R3 or later. If immediate patching is not possible, evaluate whether Enhanced Subscriber Management for DHCPv6 can be temporarily disabled as a compensating control.
- Consultation2.0 h
- Implementation3.0 h
- Testing3.0 h
- Review / QA2.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2017-2340 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2017-2340 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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