Loading
An issue was discovered on Zyxel GS1900 devices with firmware before 2.50(AAHH.0)C0. Through an undocumented sequence of keypresses, undocumented functionality is triggered. A diagnostics shell is triggered via CTRL-ALT-t, which prompts for the password returned by fds_sys_passDebugPasswd_ret(). The firmware contains access control checks that determine if remote users are allowed to access this functionality. The function that performs this check (fds_sys_remoteDebugEnable_ret in libfds.so) always return TRUE with no actual checks performed. The diagnostics menu allows for reading/writing arbitrary registers and various other configuration parameters which are believed to be related to the network interface chips.
Use CWE-287, Zyxel vendor hub and Gs1900-8 Firmware product page to widen CVE-2019-15803 into its surrounding weakness, vendor, and product context.
Compare it with CVE-2019-15804, CVE-2024-8881 and CVE-2021-35031 for nearby disclosures in the same product family.