diff --git a/src/Symfony/Component/Validator/Constraints/LocaleValidator.php b/src/Symfony/Component/Validator/Constraints/LocaleValidator.php
index 4cd0b120b4f67..11045ca95f60e 100644
--- a/src/Symfony/Component/Validator/Constraints/LocaleValidator.php
+++ b/src/Symfony/Component/Validator/Constraints/LocaleValidator.php
@@ -47,7 +47,7 @@ public function validate(mixed $value, Constraint $constraint)
             $value = \Locale::canonicalize($value);
         }
 
-        if (!Locales::exists($value)) {
+        if (null === $value || !Locales::exists($value)) {
             $this->context->buildViolation($constraint->message)
                 ->setParameter('{{ value }}', $this->formatValue($inputValue))
                 ->setCode(Locale::NO_SUCH_LOCALE_ERROR)
diff --git a/src/Symfony/Component/Validator/Tests/Constraints/LocaleValidatorTest.php b/src/Symfony/Component/Validator/Tests/Constraints/LocaleValidatorTest.php
index 4eec91c63d683..fe3594eb47740 100644
--- a/src/Symfony/Component/Validator/Tests/Constraints/LocaleValidatorTest.php
+++ b/src/Symfony/Component/Validator/Tests/Constraints/LocaleValidatorTest.php
@@ -91,6 +91,21 @@ public static function getInvalidLocales()
         ];
     }
 
+    public function testTooLongLocale()
+    {
+        $constraint = new Locale([
+            'message' => 'myMessage',
+        ]);
+
+        $locale = str_repeat('a', (\defined('INTL_MAX_LOCALE_LEN') ? \INTL_MAX_LOCALE_LEN : 85) + 1);
+        $this->validator->validate($locale, $constraint);
+
+        $this->buildViolation('myMessage')
+            ->setParameter('{{ value }}', '"' . $locale . '"')
+            ->setCode(Locale::NO_SUCH_LOCALE_ERROR)
+            ->assertRaised();
+    }
+
     /**
      * @dataProvider getUncanonicalizedLocales
      */