What’s Vulnerable › Vulnerabilities

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

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-12-05 · updated 2026-06-17
• Weakness: CWE-321

Description

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.

Affected products

• Advantech Co., Ltd. WISE-DeviceOn Server: before 5.4 — fixed in 5.4

How to fix

Upgrade to a fixed version: Advantech Co., Ltd. WISE-DeviceOn Server 5.4. Check the vendor advisory for mitigations.

References

• https://advcloudfiles.advantech.com/cms/2ca1b071-fd78-4d7f-8a2a-7b4537a95d19/Security%20Advisory%20PDF%20File/SECURITY-ADVISORY----DeviceOn-20251208-2.pdf
• https://docs.deviceon.advantech.com/docs/resource/
• https://pellera.com/blog/advantech-wise-deviceon-cve-2025-34256-vulnerability/
• https://www.vulncheck.com/advisories/advantech-wise-deviceon-server-hardcoded-jwt-key-authentication-bypass

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