{"id":"CVE-2019-15803","url":"https://www.cyber-defence.io/tools/cve/CVE-2019-15803","generatedAt":"2026-10-29T00:43:16.096Z","title":"The firmware contains access control checks that determine if remote users are allowed to access this functionality.","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.","published":"2019-11-14T21:15:12.000Z","lastModified":"2026-06-17T02:21:06.000Z","status":"Modified","sourceIdentifier":"cve@mitre.org","cvss":{"version":"3.1","score":9.1,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N"},"cwe":["CWE-287"],"affected":["zyxel/gs1900-8 firmware","zyxel/gs1900-8hp firmware","zyxel/gs1900-10hp firmware","zyxel/gs1900-16 firmware","zyxel/gs1900-24e firmware","zyxel/gs1900-24 firmware","zyxel/gs1900-24hp firmware","zyxel/gs1900-48 firmware","zyxel/gs1900-48hp firmware"],"epss":{"score":0.01323,"percentile":0.70756,"date":"2026-10-27","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (1.32%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://jasper.la/exploring-zyxel-gs1900-firmware-with-ghidra.html","tags":["Exploit","Third Party Advisory"],"source":"cve@mitre.org"},{"url":"https://www.zyxel.com/support/gs1900-switch-vulnerabilities.shtml","tags":["Vendor Advisory"],"source":"cve@mitre.org"},{"url":"https://jasper.la/exploring-zyxel-gs1900-firmware-with-ghidra.html","tags":["Exploit","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.zyxel.com/support/gs1900-switch-vulnerabilities.shtml","tags":["Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2019-15803","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}