diff --git a/framework/CHANGELOG.md b/framework/CHANGELOG.md
index 0ba9ed89fe..c0679e2c93 100644
--- a/framework/CHANGELOG.md
+++ b/framework/CHANGELOG.md
@@ -43,6 +43,7 @@ Yii Framework 2 Change Log
 - Enh #19526: Add the `convertIniSizeToBytes` method to `BaseStringHelper` (max-s-lab)
 - Bug #20570: Fix `@var` annotation for `UrlManager::$cache` (max-s-lab)
 - Bug #20571: Fix `@var` annotation for `yii\web\Response::$stream` (max-s-lab)
+- Bug #20576: Fix `@var` annotation for `StringValidator::$length` (max-s-lab)
 
 
 2.0.53 June 27, 2025
diff --git a/framework/validators/StringValidator.php b/framework/validators/StringValidator.php
index 463cc5cb0a..ce9cdd4b26 100644
--- a/framework/validators/StringValidator.php
+++ b/framework/validators/StringValidator.php
@@ -21,7 +21,7 @@ use yii\helpers\Json;
 class StringValidator extends Validator
 {
     /**
-     * @var int|array specifies the length limit of the value to be validated.
+     * @var int|array|null specifies the length limit of the value to be validated.
      * This can be specified in one of the following forms:
      *
      * - an integer: the exact length that the value should be of;