diff --git a/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php b/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php
--- a/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php
+++ b/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php
@@ -1053,13 +1053,30 @@
       $phids = array_diff($phids, $this->subscribers);
     }
 
-    foreach ($phids as $key => $phid) {
-      if ($object->isAutomaticallySubscribed($phid)) {
-        unset($phids[$key]);
+    if ($phids) {
+      $users = id(new PhabricatorPeopleQuery())
+        ->withPHIDs($phids)
+        ->loadPage();
+      $users = mpull($users, null, 'getPHID');
+
+      foreach ($phids as $key => $phid) {
+        // Do not subscribe mentioned users
+        // who do not have VIEW Permissions
+        if (!PhabricatorPolicyFilter::hasCapability(
+          $users[$phid],
+          $object,
+          PhabricatorPolicyCapability::CAN_VIEW)
+        ) {
+          unset($phids[$key]);
+        } else {
+          if ($object->isAutomaticallySubscribed($phid)) {
+            unset($phids[$key]);
+          }
+        }
       }
+      $phids = array_values($phids);
     }
-    $phids = array_values($phids);
-
+    // No else here to properly return null should we unset all subscriber
     if (!$phids) {
       return null;
     }