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Fencer Intel
critical 9.1

CVE-2020-28899 json

The Web CGI Script on ZyXEL LTE4506-M606 V1.00(ABDO.2)C0 devices does not require authentication, which allows remote unauthenticated attac…

published 5y ago modified 4mo ago also EUVD-2020-21290

cvss
9.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.7%
EPSS 1.7% chance of exploitation in 30 days, percentile 77%
public exploits
0
none known

Summary

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.

Patch / fix

  • zyxel lte4506-m606_firmware v1.00\(abdo.6\)c0
  • zyxel lte7460-m608_firmware v1.00\(abfr.5\)c0
  • zyxel wah7706_firmware v1.00\(abbc.11\)c0

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Exploit prediction

1.69% chance of exploitation in the next 30 days, higher than 77% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
NVD 2.0 6.4 AV:N/AC:L/Au:N/C:P/I:P/A:N

Classification

Weakness
  • CWE-306 Missing Authentication for Critical Functionality

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.