CVE-2020-29583

Exp

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.

Published: 2020-12-22 Last update: 2025-11-07 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-29583 is rated Critical Active Threat (94.8/100): CVSS Critical severity, with high exploitation likelihood (EPSS 90.05%, 100th percentile). CISA KEV confirms active exploitation (added 2021-11-03) affecting Zyxel / Multiple Products. a weakness (CWE-522) Unauthenticated remote administrative access may be possible. The CISA remediation deadline has passed—treat as an emergency patch priority.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

CISA KEV Record for CVE-2020-29583

Name: Zyxel Multiple Products Use of Hard-Coded Credentials Vulnerability · CISA KEV detail

Exploit added: 2021-11-03

Action due: 2022-05-03

Required action: Apply updates per vendor instructions.

Public exploit references (Exploit-DB) for CVE-2020-29583

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2020-29583

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 94.33% 90.05% -4.28%
2 2026-05-20 94.37% 94.33% -0.04%
3 2025-12-23 — 94.37% —

Full EPSS history (30 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-29583

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 134c704f-9b21-4f2e-91b3-4a467353bcc0
10.0 2.0 HIGH
AV:N/AC:L/Au:N/C:C/I:C/A:C Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:C)
Complete confidentiality impact.
Integrity impact (I:C)
Complete integrity impact.
Availability impact (A:C)
Complete availability impact.
 10.0 10.0 [email protected]

Weakness enumeration for CVE-2020-29583

Affected software / configurations for CVE-2020-29583

Vendor Product Version Raw CPE
zyxel usg20-vpn_firmware 4.60 cpe:2.3:o:zyxel:usg20-vpn_firmware:4.60:*:*:*:*:*:*:*
zyxel usg20w-vpn_firmware 4.60 cpe:2.3:o:zyxel:usg20w-vpn_firmware:4.60:*:*:*:*:*:*:*
zyxel usg40_firmware 4.60 cpe:2.3:o:zyxel:usg40_firmware:4.60:*:*:*:*:*:*:*
zyxel usg40w_firmware 4.60 cpe:2.3:o:zyxel:usg40w_firmware:4.60:*:*:*:*:*:*:*
zyxel usg60_firmware 4.60 cpe:2.3:o:zyxel:usg60_firmware:4.60:*:*:*:*:*:*:*
zyxel usg60w_firmware 4.60 cpe:2.3:o:zyxel:usg60w_firmware:4.60:*:*:*:*:*:*:*
zyxel usg110_firmware 4.60 cpe:2.3:o:zyxel:usg110_firmware:4.60:*:*:*:*:*:*:*
zyxel usg210_firmware 4.60 cpe:2.3:o:zyxel:usg210_firmware:4.60:*:*:*:*:*:*:*
zyxel usg310_firmware 4.60 cpe:2.3:o:zyxel:usg310_firmware:4.60:*:*:*:*:*:*:*
zyxel usg1100_firmware 4.60 cpe:2.3:o:zyxel:usg1100_firmware:4.60:*:*:*:*:*:*:*
zyxel usg1900_firmware 4.60 cpe:2.3:o:zyxel:usg1900_firmware:4.60:*:*:*:*:*:*:*
zyxel usg2200_firmware 4.60 cpe:2.3:o:zyxel:usg2200_firmware:4.60:*:*:*:*:*:*:*
zyxel zywall110_firmware 4.60 cpe:2.3:o:zyxel:zywall110_firmware:4.60:*:*:*:*:*:*:*
zyxel zywall310_firmware 4.60 cpe:2.3:o:zyxel:zywall310_firmware:4.60:*:*:*:*:*:*:*
zyxel zywall1100_firmware 4.60 cpe:2.3:o:zyxel:zywall1100_firmware:4.60:*:*:*:*:*:*:*
zyxel atp100_firmware 4.60 cpe:2.3:o:zyxel:atp100_firmware:4.60:*:*:*:*:*:*:*
zyxel atp100w_firmware 4.60 cpe:2.3:o:zyxel:atp100w_firmware:4.60:*:*:*:*:*:*:*
zyxel atp200_firmware 4.60 cpe:2.3:o:zyxel:atp200_firmware:4.60:*:*:*:*:*:*:*
zyxel atp500_firmware 4.60 cpe:2.3:o:zyxel:atp500_firmware:4.60:*:*:*:*:*:*:*
zyxel atp700_firmware 4.60 cpe:2.3:o:zyxel:atp700_firmware:4.60:*:*:*:*:*:*:*
zyxel atp800_firmware 4.60 cpe:2.3:o:zyxel:atp800_firmware:4.60:*:*:*:*:*:*:*
zyxel vpn50_firmware 4.60 cpe:2.3:o:zyxel:vpn50_firmware:4.60:*:*:*:*:*:*:*
zyxel vpn100_firmware 4.60 cpe:2.3:o:zyxel:vpn100_firmware:4.60:*:*:*:*:*:*:*
zyxel vpn300_firmware 4.60 cpe:2.3:o:zyxel:vpn300_firmware:4.60:*:*:*:*:*:*:*
zyxel vpn1000_firmware 4.60 cpe:2.3:o:zyxel:vpn1000_firmware:4.60:*:*:*:*:*:*:*
zyxel usg_flex_100_firmware 4.60 cpe:2.3:o:zyxel:usg_flex_100_firmware:4.60:*:*:*:*:*:*:*
zyxel usg_flex_100w_firmware 4.60 cpe:2.3:o:zyxel:usg_flex_100w_firmware:4.60:*:*:*:*:*:*:*
zyxel usg_flex_200_firmware 4.60 cpe:2.3:o:zyxel:usg_flex_200_firmware:4.60:*:*:*:*:*:*:*
zyxel usg_flex_500_firmware 4.60 cpe:2.3:o:zyxel:usg_flex_500_firmware:4.60:*:*:*:*:*:*:*
zyxel usg_flex_700_firmware 4.60 cpe:2.3:o:zyxel:usg_flex_700_firmware:4.60:*:*:*:*:*:*:*

References for CVE-2020-29583

URL Tags
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
cvelogic Threat Intelligence