diff --git a/system/Config/Services.php b/system/Config/Services.php
index 5ffb9e049c46..738809b44595 100644
--- a/system/Config/Services.php
+++ b/system/Config/Services.php
@@ -690,6 +690,12 @@ public static function session(?SessionConfig $config = null, bool $getShared =
         $session->setLogger($logger);
 
         if (session_status() === PHP_SESSION_NONE) {
+            // PHP Session emits the headers according to `session.cache_limiter`.
+            // See https://www.php.net/manual/en/function.session-cache-limiter.php.
+            // The headers are not managed by CI's Response class.
+            // So, we remove CI's default Cache-Control header.
+            AppServices::response()->removeHeader('Cache-Control');
+
             $session->start();
         }