FlowiseAI: CustomTemplate create+update mass-assignment allows cross-workspace template takeover

Summary

Type: Mass assignment via Object.assign(entity, body) -> client-controlled workspaceId (and on create, id) overwritten on the CustomTemplate entity -> cross-workspace data takeover and IDOR. File: packages/server/src/services/marketplaces/index.ts Root cause: The CustomTemplate controller/service constructs a new CustomTemplate() and copies the request body into it via Object.assign(...) without an explicit field allowlist. The request body therefore can include workspaceId, id, createdDate, updatedDate. The server only rebinds some of these after the assign (e.g. on create, it overwrites workspaceId but not id; on update, it overwrites id but not workspaceId). The remaining client-controlled values land directly on the persisted row, breaking workspace isolation. Same root pattern as the customtemplate entity's sibling controllers and as DocumentStore before it was patched in commit 840d2ae.

Affected Code

File: packages/server/src/services/marketplaces/index.ts

// at line 211
Object.assign(newTemplate, body)        // <-- BUG: body.id, body.workspaceId accepted

Why it's wrong: Object.assign(target, source) copies every own enumerable property of source onto target. The TypeORM/SQL persistence layer below it does not strip ownership-bearing columns, so workspaceId set in the request body lands as the new workspaceId of the persisted row. The DocumentStore patch (commit 840d2ae) demonstrated the intended fix shape (explicit field-by-field allowlist) but it has not been applied to this entity.

Exploit Chain

1. Attacker is an authenticated member of workspace A. They have a session cookie / JWT for the Flowise web UI. State at this point: attacker can read and write entities scoped to workspace A.
2. Attacker creates a customtemplate in workspace A via the documented API (or reuses an existing one they own). They note its entity id.
3. Attacker issues a PUT /api/v1/customtemplates/<id> (or equivalent endpoint) with a JSON body that includes "workspaceId": "<workspace-B-id>" (an arbitrary other workspace's UUID). State at this point: the request reaches the controller as a workspace-A authenticated request.