diff --git a/src/Symfony/Component/Validator/Mapping/Loader/AbstractLoader.php b/src/Symfony/Component/Validator/Mapping/Loader/AbstractLoader.php
index 67b7b20101a7f..0910d8bf873d3 100644
--- a/src/Symfony/Component/Validator/Mapping/Loader/AbstractLoader.php
+++ b/src/Symfony/Component/Validator/Mapping/Loader/AbstractLoader.php
@@ -101,6 +101,15 @@ protected function newConstraint(string $name, mixed $options = null): Constrain
                 return new $className($options);
             }
 
+            if (isset($options['value']) && \in_array($name, ['Length', 'Count'], true)) {
+                trigger_deprecation('symfony/validator', '7.3', 'Using the "value" option in configuration for the "%s" constraint is deprecated. Use "exactly" instead.', $name);
+
+                if (!isset($options['exactly'])) {
+                    $options['exactly'] = $options['value'];
+                    unset($options['value']);
+                }
+            }
+
             return new $className(...$options);
         }
 
diff --git a/src/Symfony/Component/Validator/Tests/Mapping/Loader/XmlFileLoaderTest.php b/src/Symfony/Component/Validator/Tests/Mapping/Loader/XmlFileLoaderTest.php
index 08a4bb862cbf1..7e1d0849cbba9 100644
--- a/src/Symfony/Component/Validator/Tests/Mapping/Loader/XmlFileLoaderTest.php
+++ b/src/Symfony/Component/Validator/Tests/Mapping/Loader/XmlFileLoaderTest.php
@@ -18,6 +18,7 @@
 use Symfony\Component\Validator\Constraints\Choice;
 use Symfony\Component\Validator\Constraints\Collection;
 use Symfony\Component\Validator\Constraints\IsTrue;
+use Symfony\Component\Validator\Constraints\Length;
 use Symfony\Component\Validator\Constraints\NotNull;
 use Symfony\Component\Validator\Constraints\Range;
 use Symfony\Component\Validator\Constraints\Regex;
@@ -188,4 +189,22 @@ public function testLoadConstraintWithoutNamedArgumentsSupport()
 
         $loader->loadClassMetadata($metadata);
     }
+
+    /**
+     * @group legacy
+     */
+    public function testLengthConstraintValueOptionTriggersDeprecation()
+    {
+        $this->expectDeprecation('Since symfony/validator 7.3: Using the "value" option in configuration for the "Length" constraint is deprecated. Use "exactly" instead.');
+
+        $loader = new XmlFileLoader(__DIR__.'/constraint-mapping-exactly-value.xml');
+        $metadata = new ClassMetadata(Entity_81::class);
+        $loader->loadClassMetadata($metadata);
+        $constraints = $metadata->getPropertyMetadata('title')[0]->constraints;
+
+        self::assertCount(1, $constraints);
+        self::assertInstanceOf(Length::class, $constraints[0]);
+        self::assertSame(6, $constraints[0]->min);
+        self::assertSame(6, $constraints[0]->max);
+    }
 }
diff --git a/src/Symfony/Component/Validator/Tests/Mapping/Loader/constraint-mapping-exactly-value.xml b/src/Symfony/Component/Validator/Tests/Mapping/Loader/constraint-mapping-exactly-value.xml
new file mode 100644
index 0000000000000..40e04f3a368b7
--- /dev/null
+++ b/src/Symfony/Component/Validator/Tests/Mapping/Loader/constraint-mapping-exactly-value.xml
@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<constraint-mapping xmlns="http://symfony.com/schema/dic/constraint-mapping"
+                    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+                    xsi:schemaLocation="http://symfony.com/schema/dic/constraint-mapping
+                        https://symfony.com/schema/dic/constraint-mapping/constraint-mapping-1.0.xsd">
+
+    <class name="Symfony\Component\Validator\Tests\Fixtures\Entity_81">
+        <property name="title">
+            <constraint name="Length">
+                <option name="value">6</option>
+                <option name="groups">
+                    <value>Foo</value>
+                </option>
+            </constraint>
+        </property>
+    </class>
+</constraint-mapping>