What is CVE-2019-15803?

CVE-2019-15803 is a critical-severity vulnerability in Zyxel Gs1900-10hp, classified under Improper Authentication. CVSS score: 9.1/10. Published 2019-11-14.

How severe is CVE-2019-15803?

Critical severity. CVSS v3 base score is 9.1 out of 10.

Auth bypass in Zyxel Gs1900-10hp

CVE-2019-15803

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.

Vulnerability class: Broken Authentication

EPSS: 0.013 (69.0th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.

Affected products

Weakness classification (CWE)

CWE-287 — Improper Authentication

References

cve@mitre.org (Exploit, Third Party Advisory, x_refsource_MISC)
cve@mitre.org (x_refsource_CONFIRM, Vendor Advisory)

Frequently asked questions

What is CVE-2019-15803?: CVE-2019-15803 is a critical-severity vulnerability in Zyxel Gs1900-10hp, classified under Improper Authentication. CVSS score: 9.1/10. Published 2019-11-14.
How severe is CVE-2019-15803?: Critical severity. CVSS v3 base score is 9.1 out of 10.