TI-2026-76712 Aliases CVE-2026-12489

Zyxel EX3501-T0 incorrect authorization enables privilege escalation

LOW 31CWE-863Published 2026-10-20 · Updated 2026-11-04

Key facts

Attack vector: Network
Privileges required: Low
User interaction: None
Attack complexity: Low
Impact type: Security bypass
Confidentiality · integrity · availability: High · None · None
Fix status: No fix listed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-863.

Summary

Zyxel EX3501-T0 firmware versions through 5.44(ACHR.6)C0 are affected. An incorrect authorization flaw (CWE-863) in the Data Access Layer lets an authenticated attacker escalate privileges by modifying the login_privilege data on the device.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Description from the CNA

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.0029 21st percentileScored 2026-11-07

Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
Zyxel	EX3501-T0 firmware	up to 5.44(ACHR.6)C0	—	No fix listed	CNA

EX3501-T0 firmware VendorZyxel Affected up to 5.44(ACHR.6)C0 Fixed in — No fix listed CNA

Remediation

The sources list no fixed version for Zyxel EX3501-T0 firmware.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Timeline

2026-10-20 Threatist record created from CVE-2026-12489
2026-10-20 CISA SSVC decision points changed
2026-10-20 Priority changed: MEDIUM → LOW
2026-10-21 CISA SSVC decision points changed
2026-11-03 CISA SSVC decision points changed

References

Advisory 1

https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-incorrect-authorization-vulnerability-in-the-dal-of-certain-5g-nr-cpe-dsl-ethernet-cpe-fiber-onts-and-wireless-extenders-10-20-2026

TI-2023-16198 Buffer overflow in Zyxel ATP series firmware KEVCVSS 3.1CRITICAL 9.8
TI-2023-16197 Buffer overflow in Zyxel ATP series firmware KEVCVSS 3.1CRITICAL 9.8
TI-2023-13281 OS command injection in Zyxel ZyWALL/USG series firmware KEVCVSS 3.1CRITICAL 9.8
TI-2023-12582 OS command injection in Zyxel NAS326 firmware KEVCVSS 3.1CRITICAL 9.8
TI-2022-12682 OS command injection in Zyxel USG FLEX 100 firmware KEVCVSS 3.1CRITICAL 9.8
TI-2020-17772 Firmware version 4.60 of Zyxel USG devices contains an undocumented account (zyfwp) with… KEVCVSS 3.1CRITICAL 9.8

See all 340 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences