diff --git a/app/jobs/card/clean_inaccessible_data_job.rb b/app/jobs/card/clean_inaccessible_data_job.rb
new file mode 100644
index 000000000..c3fbef936
--- /dev/null
+++ b/app/jobs/card/clean_inaccessible_data_job.rb
@@ -0,0 +1,7 @@
+class Card::CleanInaccessibleDataJob < ApplicationJob
+  discard_on ActiveJob::DeserializationError
+
+  def perform(card)
+    card.clean_inaccessible_data
+  end
+end
diff --git a/app/models/card.rb b/app/models/card.rb
index 18957cb9b..d76512093 100644
--- a/app/models/card.rb
+++ b/app/models/card.rb
@@ -1,5 +1,5 @@
 class Card < ApplicationRecord
-  include Assignable, Attachments, Broadcastable, Closeable, Colored, Entropic, Eventable,
+  include Accessible, Assignable, Attachments, Broadcastable, Closeable, Colored, Entropic, Eventable,
     Exportable, Golden, Mentions, Multistep, Pinnable, Postponable, Promptable,
     Readable, Searchable, Stallable, Statuses, Storage::Tracked, Taggable, Triageable, Watchable
 
@@ -46,12 +46,6 @@ class Card < ApplicationRecord
     end
   end
 
-  delegate :accessible_to?, to: :board
-
-  def publicly_accessible?
-    published? && board.publicly_accessible?
-  end
-
   def card
     self
   end
@@ -135,16 +129,13 @@ class Card < ApplicationRecord
       end
 
       remove_inaccessible_notifications_later
+      clean_inaccessible_data_later
     end
 
     def track_board_change_event(old_board_name)
       track_event "board_changed", particulars: { old_board: old_board_name, new_board: board.name }
     end
 
-    def grant_access_to_assignees
-      board.accesses.grant_to(assignees)
-    end
-
     def assign_number
       self.number ||= account.increment!(:cards_count).cards_count
     end
diff --git a/app/models/card/accessible.rb b/app/models/card/accessible.rb
new file mode 100644
index 000000000..e74e0b914
--- /dev/null
+++ b/app/models/card/accessible.rb
@@ -0,0 +1,26 @@
+module Card::Accessible
+  extend ActiveSupport::Concern
+
+  included do
+    delegate :accessible_to?, to: :board
+  end
+
+  def publicly_accessible?
+    published? && board.publicly_accessible?
+  end
+
+  def clean_inaccessible_data
+    accessible_user_ids = board.accesses.pluck(:user_id)
+    pins.where.not(user_id: accessible_user_ids).in_batches.destroy_all
+    watches.where.not(user_id: accessible_user_ids).in_batches.destroy_all
+  end
+
+  private
+    def grant_access_to_assignees
+      board.accesses.grant_to(assignees)
+    end
+
+    def clean_inaccessible_data_later
+      Card::CleanInaccessibleDataJob.perform_later(self)
+    end
+end
diff --git a/test/models/card_test.rb b/test/models/card_test.rb
index 9c7d45add..bb72fddf8 100644
--- a/test/models/card_test.rb
+++ b/test/models/card_test.rb
@@ -163,4 +163,48 @@ class CardTest < ActiveSupport::TestCase
 
     assert_not Card.new.filled?
   end
+
+  test "pins are deleted when card moves to a board user cannot access" do
+    card = cards(:logo)
+    kevin = users(:kevin)
+    david = users(:david)
+
+    # David pins the card (Kevin already has it pinned via fixture)
+    card.pin_by(david)
+
+    assert card.pinned_by?(kevin)
+    assert card.pinned_by?(david)
+
+    # Kevin has access to the private board, David does not
+    assert boards(:private).accessible_to?(kevin)
+    assert_not boards(:private).accessible_to?(david)
+
+    perform_enqueued_jobs only: Card::CleanInaccessibleDataJob do
+      card.move_to(boards(:private))
+    end
+
+    assert card.pinned_by?(kevin), "Kevin's pin should remain (has board access)"
+    assert_not card.pinned_by?(david), "David's pin should be deleted (no board access)"
+  end
+
+  test "watches are deleted when card moves to a board user cannot access" do
+    card = cards(:logo)
+    kevin = users(:kevin)
+    david = users(:david)
+
+    # Both watch the card via fixtures
+    assert card.watched_by?(kevin)
+    assert card.watched_by?(david)
+
+    # Kevin has access to the private board, David does not
+    assert boards(:private).accessible_to?(kevin)
+    assert_not boards(:private).accessible_to?(david)
+
+    perform_enqueued_jobs only: Card::CleanInaccessibleDataJob do
+      card.move_to(boards(:private))
+    end
+
+    assert card.watched_by?(kevin), "Kevin's watch should remain (has board access)"
+    assert_not card.watched_by?(david), "David's watch should be deleted (no board access)"
+  end
 end