Zyxel Multiple Products Use of Hard-Coded Credentials Vulnerability
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…
Severity = CVSS. Probability = EPSS (FIRST). Exploitation = public signals: KEV, EUVD, ransomware, EPSS above 10 %, no account required.
Exploitation probability EPSS · FIRST
Exploitation signals 4 / 5
- KEV catalog (CISA)03 Nov 2021
- Exploited in EUVD (ENISA)03 Nov 2021
- Used by ransomwareno
- EPSS above 10 %90.2%
- No account, over the networkyes
What to do
Fix
Apply the vendor’s fix as soon as it is available.
CISA guidance: Apply updates per vendor instructions.
Meanwhile
Take the service off the internet or restrict access to it, watch the logs and look for signs of compromise.
Manufacturers (CRA)
Exploited vulnerability in your product: early warning to ENISA within 24 h, then notification within 72 h (Article 14 of the Cyber Resilience Act). The CRA explained
Description ENISA EUVD
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
Open source packages OSV
Affected libraries according to OSV, with fixed versions.
Timeline
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Published
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Exploitation reported (ENISA)
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Added to the KEV catalog
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CISA remediation due date
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EPSS peak: 90.2%
References
Other exploited vulnerabilities from the same vendor
- CVE-2026-7273Zyxel GS1900 Series Switches Stack-Based Buffer Overflow Vulnerability4.8 · Actively exploited
- CVE-2024-40891Zyxel DSL CPE OS Command Injection Vulnerability6.0 · Background exploitation
- CVE-2024-40890Zyxel DSL CPE OS Command Injection Vulnerability5.9 · Background exploitation
- CVE-2024-11667Zyxel Multiple Firewalls Path Traversal Vulnerability5.5 · Background exploitation
- CVE-2017-6884Zyxel EMG2926 Routers Command Injection Vulnerability6.9 · Background exploitation
- CVE-2017-18368Zyxel P660HN-T1A Routers Command Injection Vulnerability9.2 · Background exploitation