CVE-2025-34256 CRITICAL

CVE-2025-34256: Advantech WISE-DeviceOn Server < 5.4 Hard-coded JWT Key Authentication Bypass

Vendor Advantech Co., Ltd.
Product WISE-DeviceOn Server
Weakness CWE-321
Published December 5, 2025
Last update April 15, 2026

CVSS base score

10.0/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality
Integrity

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

What the vulnerability does

01Description

Advantech WISE-DeviceOn Server versions prior to 5.4 contain a hard-coded cryptographic key vulnerability. The product uses a static HS512 HMAC secret for signing EIRMMToken JWTs across all installations. The server accepts forged JWTs that need only contain a valid email claim, allowing a remote unauthenticated attacker to generate arbitrary tokens and impersonate any DeviceOn account, including the root super admin. Successful exploitation permits full administrative control of the DeviceOn instance and can be leveraged to execute code on managed agents through DeviceOn’s remote management features.

Key dates

02Disclosure timeline

December 5, 2025 CVE published
April 15, 2026 Record updated