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Fencer Vulns
high 7.5

CVE-2019-15804 json

An issue was discovered on Zyxel GS1900 devices with firmware before 2.50(AAHH.0)C0.

published 2019-11-14 6 y ago modified 2026-06-17 4 mo ago also EUVD-2019-6723

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.9%
EPSS 0.9% chance of exploitation in 30 days, percentile 60%
public exploits
0
none known

Summary

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.

Patch / fix

  • zyxel gs1900-8_firmware 2.50\(aahh.0\)c0
  • zyxel gs1900-8hp_firmware 2.50\(aahi.0\)c0
  • zyxel gs1900-10hp_firmware 2.50\(aazi.0\)c0
  • zyxel gs1900-16_firmware 2.50\(aahj.0\)c0
  • zyxel gs1900-24e_firmware 2.50\(aahk.0\)c0
  • zyxel gs1900-24_firmware 2.50\(aahl.0\)c0
  • zyxel gs1900-24hp_firmware 2.50\(aahm.0\)c0
  • zyxel gs1900-48_firmware 2.50\(aahn.0\)c0
  • zyxel gs1900-48hp_firmware 2.50\(aaho.0\)c0

Exploit prediction

0.93% chance of exploitation in the next 30 days, higher than 60% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • jasper.la https://jasper.la/exploring-zyxel-gs1900-firmware-with-ghidra.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:P/A:N

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.