CVE-2019-15803

Public Exploit

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.

Category

9.1
CVSS
Severity: Critical
CVSS 3.1 •
CVSS 2.0 •
EPSS 0.38%
Vendor Advisory zyxel.com
Affected: n/a n/a
Published at:
Updated at:

References

Link Tags
https://jasper.la/exploring-zyxel-gs1900-firmware-with-ghidra.html third party advisory exploit
https://www.zyxel.com/support/gs1900-switch-vulnerabilities.shtml vendor advisory

Frequently Asked Questions

What is the severity of CVE-2019-15803?
CVE-2019-15803 has been scored as a critical severity vulnerability.
How to fix CVE-2019-15803?
To fix CVE-2019-15803, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2019-15803 being actively exploited in the wild?
It is possible that CVE-2019-15803 is being exploited or will be exploited in a near future based on public information. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
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