CVE-2020-29583: Zyxel Multiple Products Use of Hard-Coded Credentials Vulnerability

Vulnerability summary

CVE-2020-29583 is a high (CVSS 10.0) Insufficiently Protected Credentials vulnerability in Zyxel Multiple Products. It is known to be exploited: CISA lists it, first on 03-11-2021. EPSS estimates a 90.16% chance of exploitation in the next 30 days, higher than 99.7% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 22-12-2020
   PublishedVulnerability first disclosed.
2. 03-11-2021
   Added to CISA KEVZyxel Multiple Products Use of Hard-Coded Credentials Vulnerability
3. 03-05-2022
   CISA remediation dueApply updates per vendor instructions.
4. 21-10-2025
   Last modifiedVulnerability information updated.

Description

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.

• CWE-522Insufficiently Protected CredentialsThe product transmits or stores authentication credentials, but it uses an insecure method that is susceptible to unauthorized interception and/or retrieval.