CVE intelligence and bounded remediation

CVE-2025-0890 — Zyxel Vmg4325-B10A Firmware security vulnerability

Critical CVSS 9.8

**UNSUPPORTED WHEN ASSIGNED** Insecure default credentials for the Telnet function in the legacy DSL CPE Zyxel VMG4325-B10A firmware version 1.00(AAFR.4)C0_20170615 could allow an attacker to log in to the management interface if the administrators have the option to change the default credentials but fail to do so.

Severity
Critical
CVSS
9.8 (3.1)
Published
2025-02-04
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-287, CWE-522

Affected products

  • zyxel / vmg4325-b10a_firmware
  • zyxel / sbg3500-n000_firmware
  • zyxel / vmg1312-b10a_firmware
  • zyxel / vmg1312-b10b_firmware
  • zyxel / vmg1312-b10e_firmware
  • zyxel / vmg3312-b10a_firmware

Showing 6 representative product identities from 15 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Authentication bypass and missing authentication

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Check exposure

  • Map every affected endpoint and protocol path, including alternate ports, legacy routes, recovery flows, service accounts, and machine-to-machine access.
  • Confirm which deployments enable the affected authentication mode and whether the interface is reachable from untrusted networks.
  • Review session, token, credential, and proxy trust configuration without attempting account takeover.

Remediate safely

  • Apply the supported fix and centralize fail-closed authentication before protected request handling.
  • Remove default or embedded credentials, rotate affected secrets and sessions, and bind authentication decisions to the intended audience and channel.
  • Add negative tests for alternate routes, malformed or absent credentials, recovery flows, and proxy-derived identity.

Authoritative sources

Complete CVE record and remediation plan

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