CVE-2020-29583
CriticalExploitedPublic exploitFirmware version 4.60 of Zyxel USG devices contains an undocumented account (zyfwp) with an unchangeable password.
Published Jan 11, 2021 · Updated Oct 21, 2025 · Also known as TR-21-0021
Key Facts
Patch immediately- CVE-2020-29583 is a critical-severity vulnerability (CVSS 9.8 v3.1) affecting Atp100 Firmware (Zyxel), Atp100w Firmware (Zyxel), Atp200 Firmware (Zyxel) and 22 more products.
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Nov 3, 2021. Public exploit code is available.
- EPSS estimates a 90% probability of exploitation in the next 30 days.
- No fixed version is listed yet; check the vendor advisory for mitigations.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
9.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
90%
Higher than 99.7% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2020-29583 brief as a PDF
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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.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Nov 3, 2021 | May 3, 2022 | Not reported |
| Industry KEV feed | Nov 3, 2021 | May 3, 2022 | Not reported |
| CIRCL KEV | Nov 3, 2021 | May 3, 2022 | Not reported |
| ENISA EUVD | Nov 3, 2021 | n/a | Not reported |
Required action: Apply updates per vendor instructions.
Affected Products
30 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Atp100 FirmwareZyxel | 4.60 | n/a |
| Atp100w FirmwareZyxel | 4.60 | n/a |
| Atp200 FirmwareZyxel | 4.60 | n/a |
| Atp500 FirmwareZyxel | 4.60 | n/a |
| Atp700 FirmwareZyxel | 4.60 | n/a |
Timeline
Publicly disclosed
Jan 11, 2021
Added to CISA KEV
Nov 3, 2021
Added to Industry KEV feed
Nov 3, 2021
Added to CIRCL KEV
Nov 3, 2021
Added to ENISA EUVD
Nov 3, 2021
Last updated
Oct 21, 2025
Weakness Type
- CWE-522 Insufficiently Protected Credentials
References
- advisoryhttps://us-cert.cisa.gov/ncas/current-activity/2021/01/08/ms-isac-releases-cybersecurity-advisory-zyxel-firewalls-and-apMS-ISAC
- advisoryhttps://www.cyber.nj.gov/alerts-advisories/threat-actors-actively-scanning-for-vulnerable-zyxel-devices/
- advisoryhttps://www.eyecontrol.nl/blog/undocumented-user-account-in-zyxel-products.html
- advisoryUSOM advisory
- advisoryhttps://www.zyxel.com/support/CVE-2020-29583.shtml
FAQ
Common Questions.
Firmware version 4.60 of Zyxel USG devices contains an undocumented account (zyfwp) with an unchangeable password.
Affected: Atp100 Firmware (Zyxel) versions 4.60; Atp100w Firmware (Zyxel) versions 4.60; Atp200 Firmware (Zyxel) versions 4.60, among others. The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Nov 3, 2021.
Yes. It was added on Nov 3, 2021 with a federal remediation due date of May 3, 2022.
Public exploit code is available.
No fixed version is listed yet; check the vendor advisory for mitigations.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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