Critical exploit reference

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

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.

Published Dec 5, 2025 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: VulnCheck

Moderate

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.7% (30-day exploitation probability)+8
Technical severity (critical)+10
CISA SSVC: exploitation "poc"+5
Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.69%

ahead of 52% of scored CVEs · Oct 14, 2026

Affects

Advantech

Wise-deviceon Server

CVSS base

9.8

Critical · 3 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

Proof of concept

none · proof-of-concept · active

Automatable

Yes

can an attacker script the kill-chain steps

Technical impact

Total

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Advantech Wise-deviceon Server).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Advantech	Wise-deviceon Server	< 5.4	Vulnerable	NIST National Vulnerability Database
Advantech	Wise-deviceon Server	< 5.4.0	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
10.0	CVSS 4.0	Critical	—	—	disclosure@vulncheck.com via NIST National Vulnerability Database
10.0	CVSS 4.0	Critical	—	—	VulnCheck via CVE Program (cve.org) e CISA ADP
9.8	CVSS 3.1	Critical	3.9	5.9	nvd@nist.gov via NIST National Vulnerability Database

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-321

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.69%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).

web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

2026
Affected products added · advantech co., ltd./wise-deviceon server
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 13, 2026
CVSS changed · 9.8
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · → Modified
Oct 13, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 13, 2026 · NIST National Vulnerability Database
2025
CVE published
Dec 5, 2025 · VulnCheck

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

4 on the record

advcloudfiles.advantech.com/cms/2ca1b071-fd78-4d7f-8a2a-7b4537a95d19/Security%20Advisory%20PDF%20
vendor-advisory, patch, NIST National Vulnerability Database
www.vulncheck.com/advisories/advantech-wise-deviceon-server-hardcoded-jwt-key-authentic
Third Party Advisory, third-party-advisory, NIST National Vulnerability Database
pellera.com/blog/advantech-wise-deviceon-cve-2025-34256-vulnerability/
technical-description, exploit, NIST National Vulnerability Database
docs.deviceon.advantech.com/docs/resource/
Product, product, NIST National Vulnerability Database

Elsewhere on this site

Advantech
every CVE for this vendor

CWE-321
other pages naming this weakness

Related CVEs (same products)

Medium CVE-2025-34263 Advantech WISE-DeviceOn Server < 5.4 Authenticated Stored XSS via plugin-config/dashboards/menus Dec 5, 2025
Medium CVE-2025-34264 Advantech WISE-DeviceOn Server < 5.4 Authenticated Stored XSS via dog/{agentId} Dec 5, 2025
Medium CVE-2025-34265 Advantech WISE-DeviceOn Server < 5.4 Authenticated Stored XSS via rule-engines Dec 5, 2025
Medium CVE-2025-34266 Advantech WISE-DeviceOn Server < 5.4 Authenticated Stored XSS via plugin-config/addins/menus Dec 5, 2025
Medium CVE-2025-34257 Advantech WISE-DeviceOn Server < 5.4 Authenticated Stored XSS via action/defined Dec 5, 2025
Medium CVE-2025-34258 Advantech WISE-DeviceOn Server < 5.4 Authenticated Stored XSS via devicemap/plan Dec 5, 2025

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2025-34256 is "Advantech WISE-DeviceOn Server < 5.4 Hard-coded JWT Key Authentication Bypass", rated Critical. It affects Wise-deviceon Server (Advantech); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 9.8 describes technical severity. EPSS 0.69% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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