Vulnerability 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.
CVSS Score
CRITICAL
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Zyxel | Gs1900-8 Firmware | < 2.50\(aahh.0\)c0 |
| Zyxel | Gs1900-8 | - |
| Zyxel | Gs1900-8Hp Firmware | < 2.50\(aahi.0\)c0 |
| Zyxel | Gs1900-8Hp | - |
| Zyxel | Gs1900-10Hp Firmware | < 2.50\(aazi.0\)c0 |
| Zyxel | Gs1900-10Hp | - |
| Zyxel | Gs1900-16 Firmware | < 2.50\(aahj.0\)c0 |
| Zyxel | Gs1900-16 | - |
| Zyxel | Gs1900-24E Firmware | < 2.50\(aahk.0\)c0 |
| Zyxel | Gs1900-24E | - |
| Zyxel | Gs1900-24 Firmware | < 2.50\(aahl.0\)c0 |
| Zyxel | Gs1900-24 | - |
| Zyxel | Gs1900-24Hp Firmware | < 2.50\(aahm.0\)c0 |
| Zyxel | Gs1900-24Hp | - |
| Zyxel | Gs1900-48 Firmware | < 2.50\(aahn.0\)c0 |
| Zyxel | Gs1900-48 | - |
| Zyxel | Gs1900-48Hp Firmware | < 2.50\(aaho.0\)c0 |
| Zyxel | Gs1900-48Hp | - |
Related Weaknesses (CWE)
References
- https://jasper.la/exploring-zyxel-gs1900-firmware-with-ghidra.htmlExploitThird Party Advisory
- https://www.zyxel.com/support/gs1900-switch-vulnerabilities.shtmlVendor Advisory
- https://jasper.la/exploring-zyxel-gs1900-firmware-with-ghidra.htmlExploitThird Party Advisory
- https://www.zyxel.com/support/gs1900-switch-vulnerabilities.shtmlVendor Advisory
FAQ
What is CVE-2019-15803?
CVE-2019-15803 is a vulnerability with a CVSS score of 9.1 (CRITICAL). 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 tri...
How severe is CVE-2019-15803?
CVE-2019-15803 has been rated CRITICAL with a CVSS base score of 9.1/10. This is considered a critical vulnerability requiring immediate attention.
Is there a patch for CVE-2019-15803?
Check the references section above for vendor advisories and patch information. Affected products include: Zyxel Gs1900-8 Firmware, Zyxel Gs1900-8, Zyxel Gs1900-8Hp Firmware, Zyxel Gs1900-8Hp, Zyxel Gs1900-10Hp Firmware.