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

> Remote attackers can bypass authentication using a hard-coded JWT key to impersonate any user, including admins, and execute code on managed devices.

- **Severity:** Critical 10.0 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 5 Dec 2025
- **Updated:** 14 Aug 2026
- **Also known as:** GHSA-vqjp-fh8j-rf3j

## What is CVE-2025-34256?

CVE-2025-34256 is a critical vulnerability in Advantech Co., Ltd. WISE-DeviceOn Server, published on 5 Dec 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-321 (Use of Hard-coded Cryptographic Key)

## Which versions are affected by CVE-2025-34256?

It affects 1 product.


Products: Advantech Wise-Deviceon Server.

## How do I fix CVE-2025-34256?

No fix has been published for CVE-2025-34256 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-34256 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-34256 exists.

## Other vulnerabilities in Advantech Co., Ltd. WISE-DeviceOn Server

- [CVE-2025-34257](https://insights.sbomify.com/CVE-2025-34257/): Advantech WISE-DeviceOn Server < 5.4 Authenticated Stored XSS via action/defined (medium 5.1)
- [CVE-2025-34258](https://insights.sbomify.com/CVE-2025-34258/): Advantech WISE-DeviceOn Server < 5.4 Authenticated Stored XSS via devicemap/plan (medium 5.1)
- [CVE-2025-34259](https://insights.sbomify.com/CVE-2025-34259/): Advantech WISE-DeviceOn Server < 5.4 Authenticated Stored XSS via devicemap/building (medium 5.1)
- [CVE-2025-34260](https://insights.sbomify.com/CVE-2025-34260/): Advantech WISE-DeviceOn Server < 5.4 Authenticated Stored XSS via action/schedule (medium 5.1)
- [CVE-2025-34261](https://insights.sbomify.com/CVE-2025-34261/): Advantech WISE-DeviceOn Server < 5.4 Authenticated Stored XSS via devicegroups/ (medium 5.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-34256 and fix it if it is affected.

What it is: CVE-2025-34256 is a critical vulnerability in Advantech Co., Ltd. WISE-DeviceOn Server, published on 5 Dec 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-34256 exists.

Affected product: Advantech Co., Ltd. WISE-DeviceOn Server. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-34256/ (Markdown: https://insights.sbomify.com/CVE-2025-34256/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-34256
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-34256
- OSV: https://osv.dev/vulnerability/CVE-2025-34256

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-34256/
Summaries are generated and may contain mistakes; the official description above is the record.