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Fencer Vulns
critical 9.8

CVE-2020-29583 kev in the critical feed json

Firmware version 4.60 of Zyxel USG devices contains an undocumented account (zyfwp) with an unchangeable password.

published 2020-12-22 5 y ago modified 2026-06-17 4 mo ago also EUVD-2020-21944

cvss
9.8
version 3.1, CNA
cisa kev
Exploited
added 2021-11-03
epss
90.2%
EPSS 90.2% chance of exploitation in 30 days, percentile 99.7%
public exploits
0
none known, plus a Nuclei check

Summary

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.

Patch / fix

cisa required action Apply updates per vendor instructions.

Timeline

  1. Published
  2. Added to CISA KEV
  3. CISA patch deadline
  4. CISA SSVC: exploitation active

Known exploited

Added
5 y ago
Patch by
2022-05-03 (4 y ago)
Ransomware
Not known
Required action
Apply updates per vendor instructions.
Vendor, product
Zyxel, Multiple Products
CISA name
Zyxel Multiple Products Use of Hard-Coded Credentials Vulnerability

CISA SSVC

Exploitation
Active, exploited in the wild
Automatable
yes
Technical impact
total
Assessed
20 mo ago

Exploit prediction

90.16% chance of exploitation in the next 30 days, higher than 99.7% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • Nuclei template ZyXel USG - Hardcoded Credentials nuclei detection template
  • secpod.com https://www.secpod.com/blog/a-secret-zyxel-firewall-and-ap-controllers-could-allow-for-administrative-access-cve-2020-29583/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 10.0 AV:N/AC:L/Au:N/C:C/I:C/A:C

Classification

Weakness
  • CWE-522 Insufficiently Protected Credentials

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.