What is the CVSS score of CVE-2020-29583?

CVE-2020-29583 has a CVSS 3.1 base score of 9.8 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 90.0%.

Is there a public PoC exploit available for CVE-2020-29583?

Yes, a public proof-of-concept exploit is available for CVE-2020-29583. Prioritise patching immediately. EPSS: 90.0%.

Usg2200 Firmware CVE-2020-29583

CRITICAL

Insufficiently Protected Credentials (CWE-522)

2020-12-22 cve@mitre.org

Information Disclosure Zyxel Usg2200 Firmware Atp200 Firmware Atp500 Firmware Atp800 Firmware Usg20 Vpn Firmware Usg20W Vpn Firmware Usg40 Firmware Usg40W Firmware Usg60 Firmware Usg60W Firmware Usg110 Firmware Usg210 Firmware Usg310 Firmware Usg1100 Firmware Usg1900 Firmware Vpn50 Firmware Vpn100 Firmware Vpn300 Firmware Atp100 Firmware Vpn1000 Firmware Zywall110 Firmware Zywall310 Firmware Zywall1100 Firmware Atp100W Firmware Atp700 Firmware Usg Flex 100 Firmware Usg Flex 100W Firmware Usg Flex 200 Firmware Usg Flex 500 Firmware Usg Flex 700 Firmware

9.8

CVSS 3.1 · NVD

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Vulnerability Assessment

Weakness	CWE CWE-522 OWASP Top 10:2025 A06:2025 - Insecure Design ASVS 5.0 V6 - Authentication Credential protection in transit/storage
Impact	CVSS score of 9.8 (CRITICAL). Attack characteristics: network attack vector, low complexity, no privileges required, no user interaction not required. Public proof-of-concept exploit code is available.
Exploit ScenarioDerived	A remote attacker could obtain user credentials due to weak protection mechanisms by sending crafted requests to the affected application. No authentication is required to exploit this vulnerability.

Act Now Prioritize within 24-48h. Why: CRITICAL + in CISA KEV (actively exploited), no patch available.

Exploited in the wild (CISA KEV) No patch listed yet 90.0% exploitation probability (EPSS)

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AnalysisAI

Firmware version 4.60 of Zyxel USG devices contains an undocumented account (zyfwp) with an unchangeable password. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Hash passwords with strong algorithms (bcrypt, argon2), encrypt credentials in transit and at rest, never log credentials.

Affects your stack

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Technical ContextAI · show details

This vulnerability is classified as Insufficiently Protected Credentials (CWE-522), which allows attackers to obtain user credentials due to weak protection mechanisms. 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. Affected products include: Zyxel Usg20-Vpn Firmware, Zyxel Usg20W-Vpn Firmware, Zyxel Usg40 Firmware, Zyxel Usg40W Firmware, Zyxel Usg60 Firmware. Version information: version 4.60.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 9.8 CRITICAL

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

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Added to CISA KEV

Jul 14, 2026 - 04:22 CISA

CVE Published

Dec 22, 2020 - 22:15 nvd

CRITICAL 9.8

DescriptionNVD

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.

Threat Intelligence Overview

EPSS Score

90.0%

Top 0% exploitable

Exploit

POC

Public exploit code exists

Data Quality

2 sources

Confidence: Low

NVD

CVE.org

CISA KEV

EPSS POC (1)

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity CRITICAL

CISA KEV Yes

Public POC Yes

EPSS 90.0%

Patch available No

Active threat Yes

Deciding rule

CRITICAL + in CISA KEV (actively exploited), no patch available

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Immediate

Exploitation· derived

Active

System Exposure· derived

Open

Automatable· derived

Yes

Human Impact· derived

High

Priority Score

209

Low Medium High Critical

KEV: +50

EPSS: +90

CVSS: +49

PoC: +20

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Information Disclosure MEDIUM

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

Affected Products (CPE)NVD

cpe:2.3:o:zyxel:usg20-vpn_firmware:4.60:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:usg20w-vpn_firmware:4.60:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:usg40_firmware:4.60:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:usg40w_firmware:4.60:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:usg60_firmware:4.60:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:usg60w_firmware:4.60:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:usg110_firmware:4.60:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:usg210_firmware:4.60:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:usg310_firmware:4.60:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:usg1100_firmware:4.60:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:usg1900_firmware:4.60:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:usg2200_firmware:4.60:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:zywall110_firmware:4.60:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:zywall310_firmware:4.60:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:zywall1100_firmware:4.60:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:atp100_firmware:4.60:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:atp100w_firmware:4.60:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:atp200_firmware:4.60:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:atp500_firmware:4.60:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:atp700_firmware:4.60:*:*:*:*:*:*:*

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References

Advisories & patches

ADVISORY https://www.zyxel.com/support/CVE-2020-29583.shtml ADVISORY https://www.zyxel.com/support/security_advisories.shtml REF http://ftp.zyxel.com/USG40/firmware/USG40_4.60%28AALA.1%29C0_2.pdf REF https://businessforum.zyxel.com/discussion/5252/zld-v4-60-revoke-and-wk48-firmware-release REF https://businessforum.zyxel.com/discussion/5254/whats-new-for-zld4-60-patch-1-available-on-dec-15 REF https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-29583 REF https://www.eyecontrol.nl/blog/undocumented-user-account-in-zyxel-products.html

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