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CVE-2020-29583

9.8, critical Known exploited

Zyxel Multiple Products Use of Hard-Coded Credentials Vulnerability

NVD (opens in a new tab) CVE.org (opens in a new tab) CISA KEV catalogue (opens in a new tab)
CVSS
9.8, critical critical CVSS v3.1
EPSS, next 30 days
90% higher than 99.7% of scored CVEs
Exploitation
Confirmed in the wild
Published
22 Dec 20205 years ago

Known exploited

CISA added this to the Known Exploited Vulnerabilities Catalog on 3 Nov 2021. US federal agencies had to remediate by 3 May 2022, a deadline that has passed.

Required action. Apply updates per vendor instructions.

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.

Details

Vendor
Zyxel
Product
Usg20-vpn Firmware
Weakness
CWE-522 (opens in a new tab)
Status
Analyzed
Updated
17 Jun 2026
Assigner
cve@mitre.org

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

References 8

Exploit code 1

Patches and fixes 1

Advisories 3

Other references 3

The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.

Other Zyxel CVEs

Every Zyxel CVE we hold

Same vendor in what we hold, not a known link between the flaws.

  • CVE-2026-7273 Zyxel GS1900 Series Switches Stack-Based Buffer Overflow Vulnerability KEV EPSS 3% 8.8, high
  • CVE-2024-40890 Zyxel DSL CPE OS Command Injection Vulnerability KEV EPSS 21% 8.8, high
  • CVE-2024-40891 Zyxel DSL CPE OS Command Injection Vulnerability KEV EPSS 22% 8.8, high
  • CVE-2024-11667 Zyxel Multiple Firewalls Path Traversal Vulnerability KEV EPSS 3% 9.8, critical
  • CVE-2023-27992 Zyxel Multiple NAS Devices Command Injection Vulnerability KEV EPSS 83% 9.8, critical
  • CVE-2023-33009 Zyxel Multiple Firewalls Buffer Overflow Vulnerability KEV EPSS 28% 9.8, critical
  • CVE-2023-33010 Zyxel Multiple Firewalls Buffer Overflow Vulnerability KEV EPSS 29% 9.8, critical
  • CVE-2023-28771 Zyxel Multiple Firewalls OS Command Injection Vulnerability KEV EPSS 99% 9.8, critical

Beyond this page

Is CVE-2020-29583 in your network?

This page tells you how dangerous CVE-2020-29583 is out there. Whether it sits on one of your devices, only a scan of your own network can tell. That is what our systems do, every day, for the companies we protect.

CVE-2020-29583 is in the CISA catalogue of exploited vulnerabilities: attackers are already exploiting it.

  • EXYS7600 OCELOT

    Find it before attackers do

    Ocelot scans your network on a schedule and reports every vulnerability it finds by its CVE identifier, with its CVSS score and how many of your hosts are affected. A finding like CVE-2020-29583 comes with the devices to patch.

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  • EXYS7950 KONDRA

    Detect it if it's exploited

    Until the patch is applied, Kondra monitors your network, events and endpoints in real time. It keeps an inventory of the software installed on every endpoint, and its anomaly detection rules flag what an attacker does once inside.

    Learn more about EXYS7950 KONDRA
Check your exposure

Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 17 Oct 2026, not the live upstream state.