diff --git a/packages/platform/src/platform.ts b/packages/platform/src/platform.ts
index 1dee622126..a3204d91df 100644
--- a/packages/platform/src/platform.ts
+++ b/packages/platform/src/platform.ts
@@ -147,6 +147,7 @@ export default plugin(platformId, {
     InternalServerError: '' as StatusCode,
     MaintenanceWarning: '' as StatusCode<{ time: number }>,
     AccountNotFound: '' as StatusCode<{ account?: string }>,
+    AccountMismatch: '' as StatusCode<{ account?: string, requiredAccount?: string }>,
     AccountNotConfirmed: '' as StatusCode,
     WorkspaceNotFound: '' as StatusCode<{ workspaceUuid?: string, workspaceName?: string, workspaceUrl?: string }>,
     WorkspaceArchived: '' as StatusCode<{ workspaceUuid: string }>,
diff --git a/server/middleware/src/identity.ts b/server/middleware/src/identity.ts
new file mode 100644
index 0000000000..c947268a20
--- /dev/null
+++ b/server/middleware/src/identity.ts
@@ -0,0 +1,63 @@
+//
+// Copyright © 2025 Hardcore Engineering Inc.
+//
+// Licensed under the Eclipse Public License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License. You may
+// obtain a copy of the License at https://www.eclipse.org/legal/epl-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+import core, { MeasureContext, Tx, systemAccountUuid, type SessionData, type TxApplyIf } from '@hcengineering/core'
+import platform, { PlatformError, Severity, Status } from '@hcengineering/platform'
+import { BaseMiddleware, Middleware, TxMiddlewareResult, type PipelineContext } from '@hcengineering/server-core'
+
+/**
+ * @public
+ */
+export class IdentityMiddleware extends BaseMiddleware implements Middleware {
+  private constructor (context: PipelineContext, next?: Middleware) {
+    super(context, next)
+  }
+
+  static async create (
+    ctx: MeasureContext,
+    context: PipelineContext,
+    next: Middleware | undefined
+  ): Promise<IdentityMiddleware> {
+    return new IdentityMiddleware(context, next)
+  }
+
+  tx (ctx: MeasureContext<SessionData>, txes: Tx[]): Promise<TxMiddlewareResult> {
+    const account = ctx.contextData.account
+    if (account.uuid === systemAccountUuid) {
+      // TODO: We need to enhance allowed list in case of user service, on behalf of user activities.
+
+      // We pass for system accounts and services.
+      return this.provideTx(ctx, txes)
+    }
+    function checkTx (tx: Tx): void {
+      const mxAccount = ctx.contextData.socialStringsToUsers.get(tx.modifiedBy)
+      if (mxAccount === undefined || mxAccount !== account.uuid) {
+        throw new PlatformError(
+          new Status(Severity.ERROR, platform.status.AccountMismatch, {
+            account: account.uuid,
+            requiredAccount: mxAccount
+          })
+        )
+      }
+    }
+    for (const tx of txes) {
+      checkTx(tx)
+      if (tx._class === core.class.TxApplyIf) {
+        const atx = tx as TxApplyIf
+        atx.txes.forEach(checkTx)
+      }
+    }
+    return this.provideTx(ctx, txes)
+  }
+}
diff --git a/server/middleware/src/index.ts b/server/middleware/src/index.ts
index e4a4c71f3b..793e4b5509 100644
--- a/server/middleware/src/index.ts
+++ b/server/middleware/src/index.ts
@@ -36,3 +36,4 @@ export * from './spaceSecurity'
 export * from './triggers'
 export * from './txPush'
 export * from './queue'
+export * from './identity'
diff --git a/server/server-pipeline/src/pipeline.ts b/server/server-pipeline/src/pipeline.ts
index b1f3082f95..34c6c43ee2 100644
--- a/server/server-pipeline/src/pipeline.ts
+++ b/server/server-pipeline/src/pipeline.ts
@@ -23,6 +23,7 @@ import {
   DomainFindMiddleware,
   DomainTxMiddleware,
   FullTextMiddleware,
+  IdentityMiddleware,
   LiveQueryMiddleware,
   LookupMiddleware,
   LowLevelMiddleware,
@@ -116,6 +117,7 @@ export function createServerPipeline (
 
     const middlewares: MiddlewareCreator[] = [
       LookupMiddleware.create,
+      IdentityMiddleware.create,
       ModifiedMiddleware.create,
       PrivateMiddleware.create,
       NotificationsMiddleware.create,