CVE-2019-15804

An issue was discovered on Zyxel GS1900 devices with firmware before 2.50(AAHH.0)C0. By sending a signal to the CLI process, undocumented functionality is triggered. Specifically, a menu can be triggered by sending the SIGQUIT signal to the CLI application (e.g., through CTRL+\ via SSH). The access control check for this menu does work and prohibits accessing the menu, which contains "Password recovery for specific user" options. The menu is believed to be accessible using a serial console.

• https://jasper.la/exploring-zyxel-gs1900-firmware-with-ghidra.htmlExploit, Third Party Advisory
• https://www.zyxel.com/support/gs1900-switch-vulnerabilities.shtmlVendor Advisory
• https://jasper.la/exploring-zyxel-gs1900-firmware-with-ghidra.htmlExploit, Third Party Advisory
• https://www.zyxel.com/support/gs1900-switch-vulnerabilities.shtmlVendor Advisory

Published

Nov 14, 2019

Last Modified

Jun 17, 2026

Status

Modified

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