CVE-2020-1617
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 · uneditedThis issue occurs on Juniper Networks Junos OS devices which do not support Advanced Forwarding Interface (AFI) / Advanced Forwarding Toolkit (AFT). Devices using AFI and AFT are not exploitable to this issue. An improper initialization of memory in the packet forwarding architecture in Juniper Networks Junos OS non-AFI/AFT platforms which may lead to a Denial of Service (DoS) vulnerability being exploited when a genuine packet is received and inspected by non-AFT/AFI sFlow and when the device is also configured with firewall policers. This first genuine packet received and inspected by sampled flow (sFlow) through a specific firewall policer will cause the device to reboot. After the reboot has completed, if the device receives and sFlow inspects another genuine packet seen through a specific firewall policer, the device will generate a core file and reboot. Continued inspection of these genuine packets will create an extended Denial of Service (DoS) condition. Depending on the method for service restoration, e.g. hard boot or soft reboot, a core file may or may not be generated the next time the packet is received and inspected by sFlow. This issue affects: Juniper Networks Junos OS 17.4 versions prior to 17.4R2-S9, 17.4R3 on PTX1000 and PTX10000 Series, QFX10000 Series; 18.1 versions prior to 18.1R3-S9 on PTX1000 and PTX10000 Series, QFX10000 Series; 18.2X75 versions prior to 18.2X75-D12, 18.2X75-D30 on PTX1000 and PTX10000 Series, QFX10000 Series; 18.2 versions prior to 18.2R3 on PTX1000 and PTX10000 Series, QFX10000 Series; 18.3 versions prior to 18.3R3 on PTX1000 and PTX10000 Series, QFX10000 Series. This issue is not applicable to Junos OS versions before 17.4R1. This issue is not applicable to Junos OS Evolved or Junos OS with Advanced Forwarding Toolkit (AFT) forwarding implementations which use a different implementation of sFlow. The following example information is unrelated to this issue and is provided solely to assist you with determining if you have AFT or not. Example: A Junos OS device which supports the use of EVPN signaled VPWS with Flexible Cross Connect uses the AFT implementation. Since this configuration requires support and use of the AFT implementation to support this configuration, the device is not vulnerable to this issue as the sFlow implementation is different using the AFT architecture. For further details about AFT visit the AFI / AFT are in the links below. If you are uncertain if you use the AFI/AFT implementation or not, there are configuration examples in the links below which you may use to determine if you are vulnerable to this issue or not. If the commands work, you are. If not, you are not. You may also use the Feature Explorer to determine if AFI/AFT is supported or not. If you are still uncertain, please contact your support resources.
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 confidenceMemory initialization flaw in Junos OS packet forwarding on non-AFI/AFT platforms triggers device reboot when sFlow inspects genuine packets through firewall policers. The first packet causes reboot, subsequent packets generate core files and reboot, creating persistent DoS. Only affects PTX1000, PTX10000, QFX10000 series and specific 17.4-18.3 versions without AFT support.
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= 17.4= 18.1= 18.2= 18.2x75= 18.2x75-d10= 18.3CVSS 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 checksWork through these to decide whether this CVE applies to you.
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Identify the device modelRun 'show chassis hardware' or 'show system information' to confirm the hardware platformAffected if Device is NOT a PTX1000, PTX10000, or QFX10000 series (if it is different, the device is not affected)
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Check the Junos OS versionRun 'show version' to obtain the installed software versionAffected if Version matches 17.4, 18.1, 18.2, 18.2x75, 18.2x75-d10, or 18.3 (any other version is not affected)
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Determine if AFT (Advanced Fabric Termination) is in useRun 'show chassis fabric topology' or consult device documentation to verify AFT implementation statusAffected if Device does NOT have AFT support enabled (AFT implementation is not vulnerable)
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Verify sFlow configuration with firewall policersRun 'show configuration | display set | match sflow' and 'show configuration firewall' to check for sFlow inspecting traffic through policersAffected if sFlow is actively inspecting packets that pass through firewall policers (this is the trigger condition)
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Look for reboot logs or core filesRun 'show system core-dumps' and review system logs for unexpected reboits related to packet forwardingAffected if Device exhibits repeated reboots or generates core files when sFlow processes packets through firewall policers
A device is affected if it is a PTX1000, PTX10000, or QFX10000 running Junos 17.4 through 18.3 without AFT support, and sFlow is configured to inspect traffic through firewall policers.
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 to patched version (17.4R2-S9+, 17.4R3, 18.1R3-S9+, 18.2R3+, 18.3R3+) or verify device uses AFT implementation (not vulnerable). Check with 'request system software add' or Feature Explorer.
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- Review / QA2.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2020-1617 — 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-2020-1617 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
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- Version or environment caveats, and links to real fixes
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