CVE-2020-12523
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 Phoenix Contact mGuard Devices versions before 8.8.3 LAN ports get functional after reboot even if they are disabled in the device configuration. For mGuard devices with integrated switch on the LAN side, single switch ports can be disabled by device configuration. After a reboot these ports get functional independent from their configuration setting: Missing Initialization of Resource
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 confidencePhoenix Contact mGuard devices before version 8.8.3 have a missing initialization vulnerability where LAN ports that are disabled in the device configuration become enabled and functional after a reboot. This affects devices with integrated switches where individual switch ports can be disabled. The root cause is improper initialization of the port configuration state during the boot process, causing the disabled port settings to be ignored.
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< 8.8.3< 8.8.3< 8.8.3< 8.8.3all versions< 8.8.3< 8.8.3< 8.8.3CVSS 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
- High
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/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 mGuard device modelAccess the device web interface or CLI and retrieve the exact model name. Look for model numbers matching: Tc Mguard Rs4000 4g Vzw, Tc Mguard Rs4000 4g Att, Fl Mguard Rs4004 Tx/dtx, Tc Mguard Rs4000 3g, Tc Mguard Rs4000 4g, Innominate Mguard Rs4000 4tx/tx, or variants with VPN suffix.Affected if The device model is any of the listed mGuard RS4000 series variants.
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Check the installed firmware versionLog into the mGuard web interface and navigate to Status or System Information page to view the firmware version. Alternatively, use the CLI command 'show version' or access the diagnostic page.Affected if The firmware version is less than 8.8.3, or for Tc Mguard Rs4000 3g VPN, any version since all versions are affected.
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Verify the device has an integrated switch with configurable portsAccess the device configuration under Network or Switch settings. Check if the device supports disabling individual switch ports. This applies to devices with integrated switches where ports can be individually enabled or disabled.Affected if The device has an integrated switch with the ability to disable individual ports in the configuration.
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Review port configuration for disabled portsIn the device web interface, navigate to the switch port configuration section. Identify any ports that are configured as disabled or blocked in the device configuration.Affected if There are one or more ports explicitly configured as disabled in the device settings.
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Check port status after a rebootAfter rebooting the mGuard device, examine the switch port status in the web interface or via CLI. Compare the active ports against the configuration to see if previously disabled ports are now operational.Affected if Ports that were configured as disabled become active and functional after a reboot, indicating the vulnerability is present.
You are affected if you have an mGuard RS4000 series device with firmware below 8.8.3 that has an integrated switch with ports configured as disabled, and those disabled ports become enabled after a device reboot.
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.
dbcve · scoped8.8.3
Upgrade mGuard firmware to version 8.8.3 or later to address the missing initialization of port configuration. As a temporary workaround, implement network segmentation or firewall rules to restrict traffic on ports that may become unexpectedly enabled.
Firmware version 8.8.3 or later
- 1. Download the latest mGuard firmware version 8.8.3 or later from the official Phoenix Contact support portal
- 2. Access the mGuard device web interface or use the mGuard management software
- 3. Navigate to the firmware update section
- 4. Upload and apply the firmware version 8.8.3 or later
- 5. After the update completes, verify that the device restarts successfully
- 6. Log into the device and confirm that LAN port configuration settings persist correctly after a reboot
- 7. Verify that disabled LAN ports remain disabled after rebooting the device
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation6.0 h
- Implementation4.0 h
- Testing6.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-12523 — 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-2020-12523 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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- Version or environment caveats, and links to real fixes
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