Actively exploited in the wild
Zyxel Multiple Products Use of Hard-Coded Credentials Vulnerability
Zyxel - Multiple Products · Listed in the CISA KEV since 2021-11-03. This indicates confirmed attacks in production environments.
Required action: Apply updates per vendor instructions.
CVE-2020-29583
CriticalCVSS 9.8KEVSummary
Firmware version 4.60 of Zyxel USG devices contains an undocumented account (zyfwp) with an unchangeable password. The password for this account can be found in cleartext in the firmware. This account can be used by someone to login to the ssh server or web interface with admin privileges.
Risk Assessment
An attacker who knows the firmware password can log in as administrator and take full control of the device.
Recommendation
Update the firmware to a version where the account is removed or secured, and restrict access to SSH and the web interface.
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Original NVD description (English source)
Firmware version 4.60 of Zyxel USG devices contains an undocumented account (zyfwp) with an unchangeable password. The password for this account can be found in cleartext in the firmware. This account can be used by someone to login to the ssh server or web interface with admin privileges.