Security readout for executives and security teams
Plain-English summary
An authenticated user can plant malicious browser content in an AddIns menu entry. When another user views or interacts with that entry, the content may run with the victim’s WISE-DeviceOn session, potentially exposing session data or enabling unauthorized actions.
Executive priority
Schedule remediation promptly through normal vulnerability-management processes. Prioritize externally reachable systems and deployments where multiple users can manage AddIns. The vulnerability is not reported as actively exploited, but successful abuse could compromise privileged sessions and support unauthorized management actions.
Technical view
WISE-DeviceOn Server versions before 5.4 insufficiently sanitize stored label and path values submitted through /rmm/v1/plugin-config/addins/menus. The AddIns interface later renders those values, creating authenticated stored XSS. Exploitation requires low privileges and passive victim interaction; the supplied CVSS 4.0 score is 5.1.
Likely exposure
Exposure is limited to WISE-DeviceOn Server installations running versions earlier than 5.4 where untrusted or compromised authenticated users can add or edit AddIns menu entries. Internet accessibility increases opportunity, but authentication remains required. The source bundle does not identify affected deployment counts or commonly exposed configurations.
Exploitation context
The bundle reports no CISA KEV listing and provides no evidence of active exploitation. An attacker must first authenticate, store malicious content in an AddIns label or path, and wait for another user to encounter it. Consequences depend on the victim’s permissions and browser session.
Researcher notes
This is CWE-79 stored XSS with network reachability, low required privileges, and passive user interaction. The narrative range states versions before 5.4; however, the structured affected data supplied lists version “0” with default status unaffected. Confirm exact applicability against Advantech’s advisory and local version information.
Mitigation direction
- Upgrade WISE-DeviceOn Server to version 5.4 or a later vendor-supported release.
- Confirm the applicable update and deployment instructions in Advantech’s security advisory.
- Restrict AddIns configuration privileges to trusted administrators until remediation is complete.
- Review existing AddIns menu labels and paths for unexpected content.
Validation and detection
- Inventory WISE-DeviceOn Server instances and confirm each installed version.
- Verify remediated systems report version 5.4 or later.
- Confirm only authorized accounts can add or edit AddIns menu entries.
- Inspect stored AddIns configuration data and relevant audit logs for suspicious changes.
- Safely verify in testing that AddIns values are sanitized before browser rendering.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-79: User-session and phishing behavior lookup
Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2025-34266 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 5.1 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N——VulnCheckVulnerability scoring details
Base CVSS 4.0 score
5.1MediumVector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://advcloudfiles.advantech.com/cms/2ca1b071-fd78-4d7f-8a2a-7b4537a95d19/Security%20Advisory%20PDF%20File/SECURITY-ADVISORY----DeviceOn-20251208-2.pdfCVE reference, VulnCheck · vendor-advisory, patch
- https://docs.deviceon.advantech.com/docs/resource/CVE reference, VulnCheck · product
- https://www.vulncheck.com/advisories/advantech-wise-deviceon-server-authenticated-stored-xss-via-pluginconfig-addins-menusCVE reference, VulnCheck · third-party-advisory
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.