What is CVE-2026-12489?

CVE-2026-12489 is a medium-severity vulnerability in Zyxel Ex3501-T0 Firmware, classified under Incorrect Authorization. CVSS score: 6.5/10. Published 2026-10-20.

How severe is CVE-2026-12489?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Auth bypass in Zyxel Ex3501-T0 Firmware

CVE-2026-12489

An incorrect authorization vulnerability in the Data Access Layer (DAL) of Zyxel EX3501-T0 firmware versions through 5.44(ACHR.6)C0 could allow an authenticated attacker to escalate privileges by modifying the login_privilege data on an affected device.

Vulnerability class: Broken Access Control

Published 2026-10-20.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Zyxel Ex3501-T0 Firmware — versions <= 5.44(ACHR.6)C0

Weakness classification (CWE)

CWE-863 — Incorrect Authorization

References

www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for… (vendor-advisory)

Frequently asked questions

What is CVE-2026-12489?: CVE-2026-12489 is a medium-severity vulnerability in Zyxel Ex3501-T0 Firmware, classified under Incorrect Authorization. CVSS score: 6.5/10. Published 2026-10-20.
How severe is CVE-2026-12489?: Medium severity. CVSS v3 base score is 6.5 out of 10.