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

Reference page built from the source records below, each shown as its source publishes it. Dataset version ref-4ed5920a1211, updated 2026-11-02T23:39:54.475Z.

CISA Known Exploited Vulnerabilities

Name: Zyxel Multiple Products Use of Hard-Coded Credentials Vulnerability
Vendor: Zyxel
Product: Multiple Products
Added to the catalog: 2021-11-03
Due date for US federal agencies: 2022-05-03
Weaknesses: CWE-522
Catalog version: 2026.10.30

Zyxel firewalls (ATP, USG, VM) and AP Controllers (NXC2500 and NXC5500) contain a use of hard-coded credentials vulnerability in an undocumented account ("zyfwp") with an unchangeable password.

Required action (CISA)

Apply updates per vendor instructions.

Ransomware use: CISA does not mark known use of this vulnerability in ransomware campaigns.

Links in CISA's notes

https://nvd.nist.gov/vuln/detail/CVE-2020-29583

Read on 2026-11-02T23:39:54.475Z under licence cisa-kev-cc0@b0067899 from https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json

NVD analysis

Status: Analyzed
Published: 2020-12-22T22:15:14.443
Last modified: 2026-06-17T03:11:28.957
Weaknesses: CWE-522

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.

Metric	Score	Severity	Vector	Scored by
CVSS 3.1	9.8	CRITICAL	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H	[email protected] (Primary)
CVSS 3.1	9.8	CRITICAL	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H	134c704f-9b21-4f2e-91b3-4a467353bcc0 (Secondary)
CVSS 2.0	10	HIGH	AV:N/AC:L/Au:N/C:C/I:C/A:C	[email protected] (Primary)

References

http://ftp.zyxel.com/USG40/firmware/USG40_4.60%28AALA.1%29C0_2.pdf (Broken Link)
https://businessforum.zyxel.com/discussion/5252/zld-v4-60-revoke-and-wk48-firmware-release (Release Notes)
https://businessforum.zyxel.com/discussion/5254/whats-new-for-zld4-60-patch-1-available-on-dec-15 (Release Notes)
https://www.eyecontrol.nl/blog/undocumented-user-account-in-zyxel-products.html (Broken Link, Third Party Advisory)
https://www.secpod.com/blog/a-secret-zyxel-firewall-and-ap-controllers-could-allow-for-administrative-access-cve-2020-29583/ (Exploit, Third Party Advisory)
https://www.zyxel.com/support/CVE-2020-29583.shtml (Vendor Advisory)
https://www.zyxel.com/support/security_advisories.shtml (Vendor Advisory)
http://ftp.zyxel.com/USG40/firmware/USG40_4.60%28AALA.1%29C0_2.pdf (Broken Link)
https://businessforum.zyxel.com/discussion/5252/zld-v4-60-revoke-and-wk48-firmware-release (Release Notes)
https://businessforum.zyxel.com/discussion/5254/whats-new-for-zld4-60-patch-1-available-on-dec-15 (Release Notes)
https://www.eyecontrol.nl/blog/undocumented-user-account-in-zyxel-products.html (Broken Link, Third Party Advisory)
https://www.secpod.com/blog/a-secret-zyxel-firewall-and-ap-controllers-could-allow-for-administrative-access-cve-2020-29583/ (Exploit, Third Party Advisory)
https://www.zyxel.com/support/CVE-2020-29583.shtml (Vendor Advisory)
https://www.zyxel.com/support/security_advisories.shtml (Vendor Advisory)
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-29583 (US Government Resource)

This product uses the NVD API but is not endorsed or certified by the NVD.

Read on 2026-11-02T23:41:51.476Z under licence nvd-api-terms-of-use@ff2a5288 from https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2020-29583

CVE record

Assigner: mitre
State: PUBLISHED
Published: 2020-12-22T00:00:00.000Z
Updated: 2025-10-21T23:35:31.245Z
Problem types: n/a

References

Read on 2026-11-03T01:04:21.479Z under licence cve-terms-of-use@81bfa2f3 from https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2020/29xxx/CVE-2020-29583.json

Defensive techniques (MITRE D3FEND)

D3FEND maps these defensive techniques to the weakness (CWE) that NVD lists for this CVE, through the digital artifacts the weakness affects. D3FEND does not say they stop this vulnerability.

CWE-522: Insufficiently Protected Credentials

Model: Software Inventory (acts on Software)
Harden: Trusted Library (acts on Subroutine)
Model: Asset Vulnerability Enumeration (acts on Software)
Harden: Software Update (acts on Software)
Harden: Credential Scrubbing (acts on Subroutine)
Isolate: Application-based Process Isolation (acts on Subroutine)
Harden: Variable Initialization (acts on Subroutine)
Restore: Restore Software (acts on Software)
Harden: Domain Logic Validation (acts on Subroutine)

D3FEND ontology version 1.6.0.

Read on 2026-11-02T23:57:01.859Z under licence d3fend-terms-of-use@f98cbc7e from https://d3fend.mitre.org/api/weakness/cwe/CWE-522.json

MITRE D3FEND™ knowledge graph. © 2025 The MITRE Corporation.
"The MITRE Corporation (MITRE) hereby grants you a non-exclusive, royalty-free license to use D3FEND for research, development, and commercial purposes. Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." Terms: https://d3fend.mitre.org/tou/

Sources and licences

CISA
Source: CISA Catalog of Known Exploited Vulnerabilities, version 2026.10.30, CC0 1.0. Use of this data does not imply endorsement by CISA or DHS.
CC0 1.0 Universal
National Vulnerability Database (NIST)
This product uses the NVD API but is not endorsed or certified by the NVD.
NVD API Terms of Use (NIST publications in the public domain, 17 U.S.C. 105)
CVE Program, The MITRE Corporation
Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation. CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy.
CVE Program Terms of Use ("CVE Usage" licence)
MITRE D3FEND
MITRE D3FEND™ knowledge graph. © 2025 The MITRE Corporation.
"The MITRE Corporation (MITRE) hereby grants you a non-exclusive, royalty-free license to use D3FEND for research, development, and commercial purposes. Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." Terms: https://d3fend.mitre.org/tou/
MITRE D3FEND Terms of Use (site + knowledge graph); source repo MIT

Cite this page

Dragons Eye Ransomware Tracker, "CVE-2020-29583: Zyxel Multiple Products Use of Hard-Coded Credentials Vulnerability",
entity page, dataset version ref-4ed5920a1211, updated 2026-11-02T23:39:54.475Z,
https://ransomware-tracker.com/cve/CVE-2020-29583 (accessed 2026-11-03).
Underlying source: CISA Catalog of Known Exploited Vulnerabilities, version 2026.10.30.
Underlying source: National Vulnerability Database (NIST), CVE API 2.0, record last modified 2026-06-17T03:11:28.957.
Underlying source: CVE List (CVE Program, The MITRE Corporation), record updated 2025-10-21T23:35:31.245Z.
Underlying source: MITRE D3FEND, ontology version 1.6.0.

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