CVE-2020-5686
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 · uneditedIncorrect implementation of authentication algorithm issue in UNIVERGE SV9500 series from V1 to V7and SV8500 series from S6 to S8 allows an attacker to access the remote system maintenance feature and obtain the information by sending a specially crafted request to a specific URL.
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 · moderate confidenceNEC UNIVERGE SV9500 (V1-V7) and SV8500 (S6-S8) series contain an incorrectly implemented authentication algorithm in their remote system maintenance feature. Attackers can exploit this by sending specially crafted requests to a specific URL, bypassing normal authentication controls and gaining unauthorized access to retrieve sensitive system information.
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>= v1, <= v7>= s6, <= s8CVSS 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
- High
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
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 NEC UNIVERGE modelLocate the product label or access system documentation to confirm whether the device is an SV9500 or SV8500 series systemAffected if The model is an SV9500 or SV8500 series
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Check the installed firmware versionAccess the system administration interface or use the vendor-provided management tool to retrieve the current firmware version. Compare the version number to the affected ranges: SV9500 V1-V7 or SV8500 S6-S8Affected if The firmware version falls within V1 through V7 for SV9500, or S6 through S8 for SV8500
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Verify if remote system maintenance is enabledAccess the system configuration settings and check the status of the remote system maintenance feature. This is typically found under network settings, remote access settings, or maintenance configuration menusAffected if Remote system maintenance is actively enabled on the device
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Confirm network accessibility of the maintenance interfaceReview firewall rules, network ACLs, or VPN configurations to determine if the remote maintenance interface is exposed to untrusted networks. Check for open ports or NAT rules directing traffic to the maintenance serviceAffected if The maintenance interface is reachable from networks outside the trusted internal segment
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Review access logs for suspicious maintenance URL requestsExamine system logs, web server access logs, or security audit logs for unusual or anomalous requests to maintenance-related URL endpoints, particularly those that may indicate authentication bypass attemptsAffected if Logs show unexpected or unauthorized requests to maintenance URL endpoints
The environment is affected if the device is an SV9500 (V1-V7) or SV8500 (S6-S8) with remote system maintenance enabled and the maintenance interface is network-accessible.
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 dataApply vendor-supplied firmware updates (SV9500 to V8 or later, SV8500 to S9 or later). If patching is immediately unavailable, restrict network access to the maintenance interface via firewall rules or VPN, and monitor for unauthorized access attempts to the identified URL endpoints.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2020-5686 — 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-2020-5686 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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