CVE-2019-15803

CRITICAL

9.1

CVSS Score

Published: November 14, 2019 at 08:15 PM UTC

Updated: June 17, 2026 at 02:21 AM UTC

18 products affected across 1 vendorGS1900-10HP firmwareGS1900-24 firmwareGS1900-8 Firmware

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Severity

CRITICAL9.1

Exploit prediction

EPSS 1%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

GS1900-10HP firmware · Zyxel

95%

v < 2.50(aazi.0)c0

Affected range stops below 2.50(aazi.0)c0, so it looks safe — our inference, not a vendor statement

zyxel-gs1900-10hp (same device)

GS1900-16 firmware · Zyxel

95%

v < 2.50(aahj.0)c0

Affected range stops below 2.50(aahj.0)c0, so it looks safe — our inference, not a vendor statement

zyxel-gs1900-16 (same device)

GS1900-24 firmware · Zyxel

95%

v < 2.50(aahl.0)c0

Affected range stops below 2.50(aahl.0)c0, so it looks safe — our inference, not a vendor statement

zyxel-gs1900-24 (same device)

GS1900-24E firmware · Zyxel

95%

v < 2.50(aahk.0)c0

Affected range stops below 2.50(aahk.0)c0, so it looks safe — our inference, not a vendor statement

zyxel-gs1900-24e (same device)

Gs1900-24hp Firmware · Zyxel

95%

v < 2.50(aahm.0)c0

Affected range stops below 2.50(aahm.0)c0, so it looks safe — our inference, not a vendor statement

zyxel-gs1900-24hp (same device)

GS1900-48 firmware · Zyxel

95%

v < 2.50(aahn.0)c0

Affected range stops below 2.50(aahn.0)c0, so it looks safe — our inference, not a vendor statement

zyxel-gs1900-48 (same device)

Gs1900-48hp Firmware · Zyxel

95%

v < 2.50(aaho.0)c0

Affected range stops below 2.50(aaho.0)c0, so it looks safe — our inference, not a vendor statement

zyxel-gs1900-48hp (same device)

GS1900-8 Firmware · Zyxel

95%

v < 2.50(aahh.0)c0

Affected range stops below 2.50(aahh.0)c0, so it looks safe — our inference, not a vendor statement

zyxel-gs1900-8 (same device)

GS1900-8HP firmware · Zyxel

95%

v < 2.50(aahi.0)c0

Affected range stops below 2.50(aahi.0)c0, so it looks safe — our inference, not a vendor statement

zyxel-gs1900-8hp (same device)

Gs1900-10Hp · Zyxeldevice

80%

All versions

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://www.zyxel.com/support/gs1900-switch-vulnerabilities.shtml

References (2)

x_refsource_MISCExploitThird Party Advisory

Source: [email protected]

https://jasper.la/exploring-zyxel-gs1900-firmware-with-ghidra.html

x_refsource_CONFIRMVendor Advisory

Source: [email protected]

https://www.zyxel.com/support/gs1900-switch-vulnerabilities.shtml

CVSS

9.1CRITICAL[email protected]

Attack Vector: NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: HIGH
Integrity: HIGH
Availability: NONE

Vector?

Quick Info

StatusMODIFIED

CWE

CWE-287

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