diff --git a/framework/CHANGELOG.md b/framework/CHANGELOG.md
index 9b4710405a..19fc9bcb3b 100644
--- a/framework/CHANGELOG.md
+++ b/framework/CHANGELOG.md
@@ -10,6 +10,7 @@ Yii Framework 2 Change Log
 - Enh #18236: Allow `yii\filters\RateLimiter` to accept a closure function for the `$user` property in order to assign values on runtime (nadar)
 - Bug #18248: Render only one stack trace on console for chained exceptions (mikehaertl)
 - Bug #18233: Add PHP 8 support (samdark)
+- Enh #18196: `yii\rbac\DbManager::$checkAccessAssignments` is now `protected` (alex-code)
 - Bug #18239: Fix support of no-extension files for `FileValidator::validateExtension()` (darkdef)
 - Bug #18229: Add flag for recognize SyBase databases on uses pdo_dblib (darkdef)
 
diff --git a/framework/rbac/DbManager.php b/framework/rbac/DbManager.php
index b6b6f6bac8..51947bdb7b 100644
--- a/framework/rbac/DbManager.php
+++ b/framework/rbac/DbManager.php
@@ -100,7 +100,11 @@ class DbManager extends BaseManager
      * @var array auth item parent-child relationships (childName => list of parents)
      */
     protected $parents;
-
+    /**
+     * @var array user assignments (user id => Assignment[])
+     * @since `protected` since 2.0.38
+     */
+    protected $checkAccessAssignments = [];
 
     /**
      * Initializes the application component.
@@ -115,18 +119,16 @@ class DbManager extends BaseManager
         }
     }
 
-    private $_checkAccessAssignments = [];
-
     /**
      * {@inheritdoc}
      */
     public function checkAccess($userId, $permissionName, $params = [])
     {
-        if (isset($this->_checkAccessAssignments[(string) $userId])) {
-            $assignments = $this->_checkAccessAssignments[(string) $userId];
+        if (isset($this->checkAccessAssignments[(string) $userId])) {
+            $assignments = $this->checkAccessAssignments[(string) $userId];
         } else {
             $assignments = $this->getAssignments($userId);
-            $this->_checkAccessAssignments[(string) $userId] = $assignments;
+            $this->checkAccessAssignments[(string) $userId] = $assignments;
         }
 
         if ($this->hasNoAssignments($assignments)) {
@@ -857,7 +859,7 @@ class DbManager extends BaseManager
                 'created_at' => $assignment->createdAt,
             ])->execute();
 
-        unset($this->_checkAccessAssignments[(string) $userId]);
+        unset($this->checkAccessAssignments[(string) $userId]);
         return $assignment;
     }
 
@@ -870,7 +872,7 @@ class DbManager extends BaseManager
             return false;
         }
 
-        unset($this->_checkAccessAssignments[(string) $userId]);
+        unset($this->checkAccessAssignments[(string) $userId]);
         return $this->db->createCommand()
             ->delete($this->assignmentTable, ['user_id' => (string) $userId, 'item_name' => $role->name])
             ->execute() > 0;
@@ -885,7 +887,7 @@ class DbManager extends BaseManager
             return false;
         }
 
-        unset($this->_checkAccessAssignments[(string) $userId]);
+        unset($this->checkAccessAssignments[(string) $userId]);
         return $this->db->createCommand()
             ->delete($this->assignmentTable, ['user_id' => (string) $userId])
             ->execute() > 0;
@@ -970,7 +972,7 @@ class DbManager extends BaseManager
      */
     public function removeAllAssignments()
     {
-        $this->_checkAccessAssignments = [];
+        $this->checkAccessAssignments = [];
         $this->db->createCommand()->delete($this->assignmentTable)->execute();
     }
 
@@ -982,7 +984,7 @@ class DbManager extends BaseManager
             $this->rules = null;
             $this->parents = null;
         }
-        $this->_checkAccessAssignments = [];
+        $this->checkAccessAssignments = [];
     }
 
     public function loadFromCache()