CVE-2019-15803
The firmware contains access control checks that determine if remote users are allowed to access this functionality.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (1.32%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a 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.
- CVSS 3.1
- 9.1 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
- EPSS
- 1.32% probability · 69th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-287
- Affected
- zyxel/gs1900-8 firmware · zyxel/gs1900-8hp firmware · zyxel/gs1900-10hp firmware · zyxel/gs1900-16 firmware · zyxel/gs1900-24e firmware · zyxel/gs1900-24 firmware · zyxel/gs1900-24hp firmware · zyxel/gs1900-48 firmware · zyxel/gs1900-48hp firmware
- Source
- cve@mitre.org
References
- 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
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.