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

Source: https://junglewise.ai/threats/cve-2020-29583-zyxel-multiple-products-use-of-hard-coded-credentials  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2021-11-03. Updated: 2026-05-10  
License: CC BY 4.0 with a link back

CVE-2020-29583 · Severity: critical · CVSS 9.8 · Exploited in the wild · Published 2021-11-03

Zyxel firewalls and AP controllers contain an undocumented administrative account (zyfwp) with a hard-coded, unchangeable password stored in cleartext within the firmware. Remote attackers can exploit this to gain full administrative access to the device via the SSH server or web interface.

## Quick answers

**Is CVE-2020-29583 exploited in the wild?** Yes. CVE-2020-29583 is known to be exploited in the wild, first recorded on 3 November 2021. Treat it as urgent.

**How severe is CVE-2020-29583?** Critical severity, with a CVSS score of 9.8, published 3 November 2021.

**Which products and versions are affected?** Zyxel ATP Series Firewall 4.60; Zyxel USG Series Firewall 4.60; Zyxel USG FLEX Series Firewall 4.60; Zyxel VPN Series Firewall 4.60; and 2 more.

**Is there a fix for CVE-2020-29583?** A patch was published on 2020-12-15: ZLD V4.60 Patch 1 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2020-29583 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2020-29583?** Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Affected products

- Zyxel ATP Series Firewall 4.60
- Zyxel USG Series Firewall 4.60
- Zyxel USG FLEX Series Firewall 4.60
- Zyxel VPN Series Firewall 4.60
- Zyxel NXC2500 AP Controller 6.00 through 6.10
- Zyxel NXC5500 AP Controller 6.00 through 6.10

## Timeline

- 2020-12-15: patched: ZLD V4.60 Patch 1 released
- 2021-11-03: kev added: Added to CISA Known Exploited Vulnerabilities Catalog
- 2021-11-03: disclosed