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CVE Record

CVE-2020-28899: The Web CGI Script on ZyXEL LTE4506-M606 V1.00(ABDO.2)C0 devices does not require authentication, which all...

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.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2020-28899 is an authentication failure in the web CGI interface of ZyXEL LTE4506-M606 V1.00(ABDO.2)C0 routers. A remote unauthenticated attacker could use router features, including changing passwords, reading Wi-Fi passphrases, sending SMS messages, or changing forwarding rules that may expose internal networks.

Executive priority

Treat this as high priority for any exposed LTE4506-M606 router because it can undermine perimeter control and internal network separation. Prioritize internet-facing devices first, then validate firmware and vendor guidance across the fleet.

Technical view

The CVE describes unauthenticated access to /cgi-bin/gui.cgi through crafted JSON action data. The affected device and firmware named in the source bundle are ZyXEL LTE4506-M606 V1.00(ABDO.2)C0. No CVSS vector, CWE, patch version, or detailed vendor remediation text is included in the supplied bundle.

Likely exposure

Exposure is most concerning where the router web CGI/admin interface is reachable from untrusted networks or the public internet. Organizations should first look for ZyXEL LTE4506-M606 devices running V1.00(ABDO.2)C0 and determine whether remote management or web access is exposed.

Exploitation context

The provided sources do not show CISA KEV listing or confirmed active exploitation. The CVE description does say remote unauthenticated attackers can use router features via crafted JSON action data, but no exploit availability or real-world abuse is evidenced in the bundle.

Researcher notes

Key evidence is limited to the CVE description and Zyxel advisory reference. The issue is unauthenticated use of CGI functionality, not a demonstrated chain in the supplied bundle. Do not assume other Zyxel models or firmware are affected without vendor confirmation.

Mitigation direction

  • Review Zyxel's advisory and apply vendor-approved firmware or configuration guidance.
  • Remove public internet exposure for the router web CGI/admin interface.
  • Restrict management access to trusted networks or VPN-only administration.
  • Rotate router admin and Wi-Fi credentials after confirming device integrity.
  • Review forwarding, SMS, and network settings for unauthorized changes.

Validation and detection

  • Inventory ZyXEL LTE4506-M606 routers and confirm firmware versions.
  • Identify whether /cgi-bin/gui.cgi or router administration is reachable from untrusted networks.
  • Check device configuration for unexpected password, Wi-Fi, SMS, or forwarding changes.
  • Confirm remediation against Zyxel's published advisory before closing risk.
  • Document that no KEV evidence was present in the supplied sources.
Prepared
Confidence
medium
Sources
3

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

description · low confidence lookup

Credential and access behavior lookup

The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2020-28899 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
2Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.