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Lte4506 M606 FirmwareOperating system · Zyxel

CVE-2020-28899

CRITICAL · 9.1 CVSS v3.1 Published 2021-03-16
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
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
The Web CGI Script on ZyXEL LTE4506-M606 V1.00(ABDO.2)C0 devices does not require authentication, which allows remote unauthenticated attackers (via crafted JSON action data to /cgi-bin/gui.cgi) to use all features provided by the router. Examples: change the router password, retrieve the Wi-Fi passphrase, send an SMS message, or modify the IP forwarding to access the internal network.

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

The Web CGI script on ZyXEL LTE4506-M606 V1.00(ABDO.2)C0 devices has an authentication bypass vulnerability. The /cgi-bin/gui.cgi endpoint accepts crafted JSON action data without requiring any authentication, allowing remote attackers to access all administrative features of the router including password changes, Wi-Fi credential retrieval, SMS sending, and IP forwarding modifications.

MitigationApply any available firmware update from ZyXEL; if no patch exists, disable remote management interfaces from internet-facing networks and place the device behind a segmented network with strict access controls.

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
Lte4506 M606 FirmwareOperating system
Affected:< v1.00\(abdo.6\)c0
Lte7460 M608 FirmwareOperating system
Affected:< v1.00\(abfr.5\)c0
Wah7706 FirmwareOperating system
Affected:< v1.00\(abbc.11\)c0

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

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify device model and firmware version
    Access the router's web interface or check the administrative panel for the exact model number and firmware version information
    Affected if The device model is LTE4506-M606, LTE7460-M608, or Wah7706 and the firmware version is below v1.00(abdo.6)c0, v1.00(abfr.5)c0, or v1.00(abbc.11)c0 respectively
  2. Verify if the CGI endpoint is internet-accessible
    Check router firewall settings or network configuration to determine if the /cgi-bin/gui.cgi endpoint is exposed to untrusted networks
    Affected if The CGI script is reachable from untrusted networks without VPN or ACL restrictions
  3. Test the vulnerability with a benign request
    Send an unauthenticated HTTP POST request to /cgi-bin/gui.cgi with crafted JSON action data (such as a read request for system status) and observe if the device responds without rejecting the request
    Affected if The endpoint responds to unauthenticated requests with valid JSON data instead of requiring authentication

A user is affected if their device model matches one of the three listed models and the firmware version is below the fixed versions listed, with the CGI endpoint accessible to untrusted networks.

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.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply any available firmware update from ZyXEL; if no patch exists, disable remote management interfaces from internet-facing networks and place the device behind a segmented network with strict access controls.

Recommended fix High confidence

Lte4506-M606: v1.00(abdo.6)c0 or later; Lte7460-M608: v1.00(abfr.5)c0 or later; Wah7706: v1.00(abbc.11)c0 or later

  1. 1. Identify the exact model number of your ZyXEL device (Lte4506-M606, Lte7460-M608, or Wah7706)
  2. 2. Visit the official ZyXEL support website (www.zyxel.com) and navigate to the downloads/support page for your specific model
  3. 3. Download the latest firmware version: For Lte4506-M606 use v1.00(abdo.6)c0 or later; For Lte7460-M608 use v1.00(abfr.5)c0 or later; For Wah7706 use v1.00(abbc.11)c0 or later
  4. 4. Access the router's web management interface using a wired connection
  5. 5. Navigate to the Administration or Maintenance section, then to the Firmware Upgrade option
  6. 6. Upload the downloaded firmware file and initiate the upgrade process
  7. 7. Wait for the router to complete the upgrade and reboot automatically
  8. 8. After reboot, verify the firmware version has been updated in the router's status page
Caveat Firmware upgrade may reset router configuration to defaults; backup current settings before upgrade or plan to reconfigure after

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Lte4506 M606 Firmware Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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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-2020-28899 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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  • No spam, self-promotion, credentials, or personal data