diff --git a/packages/server/src/enterprise/controllers/workspace-user.controller.ts b/packages/server/src/enterprise/controllers/workspace-user.controller.ts
index 90ba4f2e2e5..b2c9945f7eb 100644
--- a/packages/server/src/enterprise/controllers/workspace-user.controller.ts
+++ b/packages/server/src/enterprise/controllers/workspace-user.controller.ts
@@ -7,6 +7,7 @@ import { getRunningExpressApp } from '../../utils/getRunningExpressApp'
 import { WorkspaceUser } from '../database/entities/workspace-user.entity'
 import { WorkspaceUserService } from '../services/workspace-user.service'
 import {
+    assertMayReadTargetUser,
     assertQueryOrganizationMatchesActiveOrg,
     assertWorkspaceIdAccessibleToUser,
     getLoggedInUser,
@@ -35,6 +36,7 @@ export class WorkspaceUserController {
 
             let workspaceUser: any
             if (query.workspaceId && query.userId) {
+                // Caller must have access to the workspace (own, assigned, or org admin within their org).
                 await assertWorkspaceIdAccessibleToUser(user, query.workspaceId, queryRunner)
                 workspaceUser = await workspaceUserService.readWorkspaceUserByWorkspaceIdUserId(
                     query.workspaceId,
@@ -42,28 +44,35 @@ export class WorkspaceUserController {
                     queryRunner
                 )
             } else if (query.workspaceId) {
+                // Caller must have access to the workspace (own, assigned, or org admin within their org).
                 await assertWorkspaceIdAccessibleToUser(user, query.workspaceId, queryRunner)
                 workspaceUser = await workspaceUserService.readWorkspaceUserByWorkspaceId(query.workspaceId, queryRunner)
             } else if (query.organizationId && query.userId) {
+                // organizationId must match the caller's active org to prevent cross-org access.
+                // Caller must be the target user or an org user manager whose target belongs to the same org (IDOR guard).
                 assertQueryOrganizationMatchesActiveOrg(user, query.organizationId)
-                if (query.userId !== user.id && !userMayManageOrgUsers(user)) {
-                    throw new InternalFlowiseError(StatusCodes.FORBIDDEN, GeneralErrorMessage.FORBIDDEN)
-                }
+                await assertMayReadTargetUser(user, query.userId, queryRunner)
                 workspaceUser = await workspaceUserService.readWorkspaceUserByOrganizationIdUserId(
                     query.organizationId,
                     query.userId,
                     queryRunner
                 )
             } else if (query.userId) {
-                if (query.userId !== user.id && !userMayManageOrgUsers(user)) {
-                    throw new InternalFlowiseError(StatusCodes.FORBIDDEN, GeneralErrorMessage.FORBIDDEN)
+                if (query.userId === user.id) {
+                    // Self-lookup: return memberships across all orgs so the user can switch to an invited org/workspace.
+                    workspaceUser = await workspaceUserService.readWorkspaceUserByUserId(query.userId, queryRunner)
+                } else {
+                    // Non-self: caller must be an org user manager and the target must belong to the caller's active org (IDOR guard).
+                    // Results are scoped to the caller's active org to prevent cross-org data leakage.
+                    await assertMayReadTargetUser(user, query.userId, queryRunner)
+                    workspaceUser = await workspaceUserService.readWorkspaceUserByOrganizationIdUserId(
+                        user.activeOrganizationId,
+                        query.userId,
+                        queryRunner
+                    )
                 }
-                workspaceUser = await workspaceUserService.readWorkspaceUserByOrganizationIdUserId(
-                    user.activeOrganizationId,
-                    query.userId,
-                    queryRunner
-                )
             } else if (query.roleId) {
+                // Only org user managers may list workspace members by role.
                 if (!userMayManageOrgUsers(user)) {
                     throw new InternalFlowiseError(StatusCodes.FORBIDDEN, GeneralErrorMessage.FORBIDDEN)
                 }