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.
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LLM-synthesized narrative grounded in this CVE's description and references.
Affected products
11- cpe:2.3:o:zyxel:gs1900-10hp_firmware:*:*:*:*:*:*:*:*Range: <2.50\(aazi.0\)c0
- cpe:2.3:o:zyxel:gs1900-24e_firmware:*:*:*:*:*:*:*:*Range: <2.50\(aahk.0\)c0
- cpe:2.3:o:zyxel:gs1900-24hp_firmware:*:*:*:*:*:*:*:*Range: <2.50\(aahm.0\)c0
- cpe:2.3:o:zyxel:gs1900-48hp_firmware:*:*:*:*:*:*:*:*Range: <2.50\(aaho.0\)c0
- cpe:2.3:o:zyxel:gs1900-8hp_firmware:*:*:*:*:*:*:*:*Range: <2.50\(aahi.0\)c0
- Zyxel/GS1900 devicesdescription
Patches
Vulnerability mechanics
References
2- jasper.la/exploring-zyxel-gs1900-firmware-with-ghidra.htmlnvdExploitThird Party Advisory
- www.zyxel.com/support/gs1900-switch-vulnerabilities.shtmlnvdVendor Advisory
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