{"id":"CVE-2019-15803","aliases":["EUVD-2019-6722","GHSA-958f-78j2-fqr6"],"status":"published","title":"An issue was discovered on Zyxel GS1900 devices with firmware before 2.50(AAHH.0)C0. Through an...","description":"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.","severity":{"version":"3.1","score":9.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","level":"critical","assessor":"primary","from":"nvd"},"epss":{"day":"2026-11-09","score":0.01323,"percentile":0.71118,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-287"],"published":"2019-11-14T20:15:56Z","modified":"2026-06-17T02:21:06Z","products":[{"vendor":"zyxel","product":"gs1900-10hp_firmware"},{"vendor":"zyxel","product":"gs1900-16_firmware"},{"vendor":"zyxel","product":"gs1900-24_firmware"},{"vendor":"zyxel","product":"gs1900-24e_firmware"},{"vendor":"zyxel","product":"gs1900-24hp_firmware"},{"vendor":"zyxel","product":"gs1900-48_firmware"},{"vendor":"zyxel","product":"gs1900-48hp_firmware"},{"vendor":"zyxel","product":"gs1900-8_firmware"},{"vendor":"zyxel","product":"gs1900-8hp_firmware"}],"references":[{"url":"https://jasper.la/exploring-zyxel-gs1900-firmware-with-ghidra.html","tags":["x_refsource_MISC","x_transferred","Exploit","Third Party Advisory"]},{"url":"https://www.zyxel.com/support/gs1900-switch-vulnerabilities.shtml","tags":["x_refsource_CONFIRM","x_transferred","Vendor Advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2019-15803"},{"url":"https://github.com/advisories/GHSA-958f-78j2-fqr6"}],"sources":{"cve":[{"id":"CVE-2019-15803","description":"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.","status":"published","published":"2019-11-14T20:15:56Z","modified":"2024-08-05T00:56:22.468Z","updated_at":"2026-11-02T14:20:21.397307Z"}],"euvd":[{"id":"EUVD-2019-6722","description":"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.","status":"published","published":"2019-11-14T20:15:56Z","modified":"2024-08-05T00:56:22Z","updated_at":"2026-11-03T02:40:34.569316Z"}],"ghsa":[{"id":"GHSA-958f-78j2-fqr6","title":"An issue was discovered on Zyxel GS1900 devices with firmware before 2.50(AAHH.0)C0. Through an...","description":"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.","status":"published","published":"2022-05-24T17:01:17Z","modified":"2023-01-28T05:07:29Z","updated_at":"2026-11-02T14:44:32.070856Z"}],"nvd":[{"id":"CVE-2019-15803","description":"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.","status":"published","published":"2019-11-14T21:15:11.89Z","modified":"2026-06-17T02:21:06.443Z","cvss":[{"version":"3.1","score":9.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","level":"critical","assessor":"primary"},{"version":"2.0","score":6.4,"vector":"AV:N/AC:L/Au:N/C:P/I:P/A:N","level":"medium","assessor":"primary"}],"cwes":["CWE-287"],"updated_at":"2026-11-02T14:05:37.024431Z"}]}}