CVE intelligence and bounded remediation

CVE-2019-15801 — An issue was discovered on Zyxel GS1900 devices with firmware before 2.50(AAHH.0)C0

High CVSS 7.5

An issue was discovered on Zyxel GS1900 devices with firmware before 2.50(AAHH.0)C0. The firmware image contains encrypted passwords that are used to authenticate users wishing to access a diagnostics or password-recovery menu. Using the hardcoded cryptographic key found elsewhere in the firmware, these passwords can be decrypted. This is related to fds_sys_passDebugPasswd_ret() and fds_sys_passRecoveryPasswd_ret() in libfds.so.0.0.

Severity
High
CVSS
7.5 (3.1)
Published
2019-11-14
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-798

Affected products

  • zyxel / gs1900-8_firmware
  • zyxel / gs1900-8hp_firmware
  • zyxel / gs1900-10hp_firmware
  • zyxel / gs1900-16_firmware
  • zyxel / gs1900-24e_firmware
  • zyxel / gs1900-24_firmware

Showing 6 representative product identities from 9 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Authentication bypass and missing authentication

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

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

The detailed catalog view below loads this exact record, its source evidence, and the full seven-phase agentic change plan.