diff --git a/Normalizer/AbstractObjectNormalizer.php b/Normalizer/AbstractObjectNormalizer.php
index 6fec439b9a0..77de6ff3fec 100644
--- a/Normalizer/AbstractObjectNormalizer.php
+++ b/Normalizer/AbstractObjectNormalizer.php
@@ -611,6 +611,8 @@ private function validateAndDenormalizeLegacy(array $types, string $currentClass
                 if (!$isUnionType && !$isNullable) {
                     throw $e;
                 }
+
+                $expectedTypes[LegacyType::BUILTIN_TYPE_OBJECT === $builtinType && $class ? $class : $builtinType] = true;
             } catch (ExtraAttributesException $e) {
                 if (!$isUnionType && !$isNullable) {
                     throw $e;
@@ -901,6 +903,8 @@ private function validateAndDenormalize(Type $type, string $currentClass, string
                 if (!$type instanceof UnionType) {
                     throw $e;
                 }
+
+                $expectedTypes[TypeIdentifier::OBJECT === $typeIdentifier && $class ? $class : $typeIdentifier->value] = true;
             } catch (ExtraAttributesException $e) {
                 if (!$type instanceof UnionType) {
                     throw $e;
diff --git a/Normalizer/GetSetMethodNormalizer.php b/Normalizer/GetSetMethodNormalizer.php
index 17731067ce6..b0ca3b4bd6d 100644
--- a/Normalizer/GetSetMethodNormalizer.php
+++ b/Normalizer/GetSetMethodNormalizer.php
@@ -169,6 +169,10 @@ protected function isAllowedAttribute($classOrObject, string $attribute, ?string
 
         $class = \is_object($classOrObject) ? $classOrObject::class : $classOrObject;
 
+        if ($this->classDiscriminatorResolver?->getMappingForMappedObject($classOrObject)?->getTypeProperty() === $attribute) {
+            return true;
+        }
+
         if (!isset(self::$reflectionCache[$class])) {
             self::$reflectionCache[$class] = new \ReflectionClass($class);
         }
diff --git a/Normalizer/ObjectNormalizer.php b/Normalizer/ObjectNormalizer.php
index 9b6ea1c322c..fc1a076fa9c 100644
--- a/Normalizer/ObjectNormalizer.php
+++ b/Normalizer/ObjectNormalizer.php
@@ -153,6 +153,10 @@ protected function isAllowedAttribute($classOrObject, string $attribute, ?string
 
         $class = \is_object($classOrObject) ? $classOrObject::class : $classOrObject;
 
+        if ($this->classDiscriminatorResolver?->getMappingForMappedObject($classOrObject)?->getTypeProperty() === $attribute) {
+            return true;
+        }
+
         if ($context['_read_attributes'] ?? true) {
             if (!isset(self::$isReadableCache[$class.$attribute])) {
                 self::$isReadableCache[$class.$attribute] = $this->propertyInfoExtractor->isReadable($class, $attribute) || $this->hasAttributeAccessorMethod($class, $attribute) || (\is_object($classOrObject) && $this->propertyAccessor->isReadable($classOrObject, $attribute));
diff --git a/Normalizer/PropertyNormalizer.php b/Normalizer/PropertyNormalizer.php
index 979e95e021e..d200d972c47 100644
--- a/Normalizer/PropertyNormalizer.php
+++ b/Normalizer/PropertyNormalizer.php
@@ -99,6 +99,10 @@ protected function isAllowedAttribute(object|string $classOrObject, string $attr
             return false;
         }
 
+        if ($this->classDiscriminatorResolver?->getMappingForMappedObject($classOrObject)?->getTypeProperty() === $attribute) {
+            return true;
+        }
+
         try {
             $reflectionProperty = $this->getReflectionProperty($classOrObject, $attribute);
         } catch (\ReflectionException) {
diff --git a/Tests/Normalizer/GetSetMethodNormalizerTest.php b/Tests/Normalizer/GetSetMethodNormalizerTest.php
index 80788a0d274..67f74d1ef41 100644
--- a/Tests/Normalizer/GetSetMethodNormalizerTest.php
+++ b/Tests/Normalizer/GetSetMethodNormalizerTest.php
@@ -569,6 +569,23 @@ public function testSupportsAndDenormalizeWithOptionalSetterArgument(array $data
         $obj = $this->normalizer->denormalize($data, GetSetDummyWithOptionalAndMultipleSetterArgs::class);
         $this->assertSame($expected, $obj->$method());
     }
+
+    public function testDiscriminatorWithAllowExtraAttributesFalse()
+    {
+        // Discriminator type property should be allowed with allow_extra_attributes=false
+        $classMetadataFactory = new ClassMetadataFactory(new AttributeLoader());
+        $discriminator = new ClassDiscriminatorFromClassMetadata($classMetadataFactory);
+        $normalizer = new GetSetMethodNormalizer($classMetadataFactory, null, null, $discriminator);
+
+        $obj = $normalizer->denormalize(
+            ['type' => 'one'],
+            GetSetMethodDummyInterface::class,
+            null,
+            [AbstractNormalizer::ALLOW_EXTRA_ATTRIBUTES => false]
+        );
+
+        $this->assertInstanceOf(GetSetMethodDiscriminatedDummyOne::class, $obj);
+    }
 }
 
 class GetSetDummy
diff --git a/Tests/Normalizer/ObjectNormalizerTest.php b/Tests/Normalizer/ObjectNormalizerTest.php
index 6b6289aa225..451a784377c 100644
--- a/Tests/Normalizer/ObjectNormalizerTest.php
+++ b/Tests/Normalizer/ObjectNormalizerTest.php
@@ -25,6 +25,7 @@
 use Symfony\Component\Serializer\Exception\NotNormalizableValueException;
 use Symfony\Component\Serializer\Exception\RuntimeException;
 use Symfony\Component\Serializer\Exception\UnexpectedValueException;
+use Symfony\Component\Serializer\Mapping\ClassDiscriminatorFromClassMetadata;
 use Symfony\Component\Serializer\Mapping\Factory\ClassMetadataFactory;
 use Symfony\Component\Serializer\Mapping\Factory\ClassMetadataFactoryInterface;
 use Symfony\Component\Serializer\Mapping\Loader\AttributeLoader;
@@ -42,6 +43,7 @@
 use Symfony\Component\Serializer\Tests\Fixtures\Attributes\GroupDummy;
 use Symfony\Component\Serializer\Tests\Fixtures\CircularReferenceDummy;
 use Symfony\Component\Serializer\Tests\Fixtures\DummyPrivatePropertyWithoutGetter;
+use Symfony\Component\Serializer\Tests\Fixtures\DummyWithUnion;
 use Symfony\Component\Serializer\Tests\Fixtures\OtherSerializedNameDummy;
 use Symfony\Component\Serializer\Tests\Fixtures\Php74Dummy;
 use Symfony\Component\Serializer\Tests\Fixtures\Php74DummyPrivate;
@@ -64,6 +66,7 @@
 use Symfony\Component\Serializer\Tests\Normalizer\Features\TypedPropertiesObject;
 use Symfony\Component\Serializer\Tests\Normalizer\Features\TypedPropertiesObjectWithGetters;
 use Symfony\Component\Serializer\Tests\Normalizer\Features\TypeEnforcementTestTrait;
+use Symfony\Component\TypeInfo\Type;
 
 /**
  * @author Kévin Dunglas <dunglas@gmail.com>
@@ -345,6 +348,27 @@ public function testConstructorWithUnknownObjectTypeHintDenormalize()
         $normalizer->denormalize($data, DummyWithConstructorInexistingObject::class);
     }
 
+    public function testConstructorWithNotMatchingUnionTypes()
+    {
+        $data = [
+            'value' => 'string',
+            'value2' => 'string',
+        ];
+        $normalizer = new ObjectNormalizer(new ClassMetadataFactory(new AttributeLoader()), null, null, new PropertyInfoExtractor([], [new ReflectionExtractor()]));
+
+        $this->expectException(NotNormalizableValueException::class);
+
+        if (class_exists(Type::class) && method_exists(PropertyInfoExtractor::class, 'getType')) {
+            $this->expectExceptionMessage('The type of the "value" attribute for class "Symfony\Component\Serializer\Tests\Fixtures\DummyWithUnion" must be one of "float", "int" ("string" given).');
+        } else {
+            $this->expectExceptionMessage('The type of the "value" attribute for class "Symfony\Component\Serializer\Tests\Fixtures\DummyWithUnion" must be one of "int", "float" ("string" given).');
+        }
+
+        $normalizer->denormalize($data, DummyWithUnion::class, 'xml', [
+            AbstractNormalizer::ALLOW_EXTRA_ATTRIBUTES => false,
+        ]);
+    }
+
     // attributes
 
     protected function getNormalizerForAttributes(): ObjectNormalizer
@@ -1086,6 +1110,23 @@ public function testPrecedenceOfAccessorMethods()
             'foo' => 'hasFoo',
         ], $normalizedSwappedHasserIsser);
     }
+
+    public function testDiscriminatorWithAllowExtraAttributesFalse()
+    {
+        // Discriminator type property should be allowed with allow_extra_attributes=false
+        $classMetadataFactory = new ClassMetadataFactory(new AttributeLoader());
+        $discriminator = new ClassDiscriminatorFromClassMetadata($classMetadataFactory);
+        $normalizer = new ObjectNormalizer($classMetadataFactory, null, null, null, $discriminator);
+
+        $obj = $normalizer->denormalize(
+            ['type' => 'type_a'],
+            DiscriminatorDummyInterface::class,
+            null,
+            [AbstractNormalizer::ALLOW_EXTRA_ATTRIBUTES => false]
+        );
+
+        $this->assertInstanceOf(DiscriminatorDummyTypeA::class, $obj);
+    }
 }
 
 class ProxyObjectDummy extends ObjectDummy
@@ -1429,6 +1470,25 @@ public function isolate()
     }
 }
 
+#[\Symfony\Component\Serializer\Attribute\DiscriminatorMap(
+    typeProperty: 'type',
+    mapping: [
+        'type_a' => DiscriminatorDummyTypeA::class,
+        'type_b' => DiscriminatorDummyTypeB::class,
+    ]
+)]
+interface DiscriminatorDummyInterface
+{
+}
+
+class DiscriminatorDummyTypeA implements DiscriminatorDummyInterface
+{
+}
+
+class DiscriminatorDummyTypeB implements DiscriminatorDummyInterface
+{
+}
+
 class ObjectWithPropertyAndAllAccessorMethods
 {
     public function __construct(
diff --git a/Tests/Normalizer/PropertyNormalizerTest.php b/Tests/Normalizer/PropertyNormalizerTest.php
index 30b8f85f056..521b8cf009f 100644
--- a/Tests/Normalizer/PropertyNormalizerTest.php
+++ b/Tests/Normalizer/PropertyNormalizerTest.php
@@ -22,6 +22,7 @@
 use Symfony\Component\Serializer\Mapping\Loader\AttributeLoader;
 use Symfony\Component\Serializer\NameConverter\CamelCaseToSnakeCaseNameConverter;
 use Symfony\Component\Serializer\NameConverter\MetadataAwareNameConverter;
+use Symfony\Component\Serializer\Normalizer\AbstractNormalizer;
 use Symfony\Component\Serializer\Normalizer\AbstractObjectNormalizer;
 use Symfony\Component\Serializer\Normalizer\ArrayDenormalizer;
 use Symfony\Component\Serializer\Normalizer\DenormalizerInterface;
@@ -585,6 +586,23 @@ public function testDenormalizeWithDiscriminator()
             )
         );
     }
+
+    public function testDiscriminatorWithAllowExtraAttributesFalse()
+    {
+        // Discriminator type property should be allowed with allow_extra_attributes=false
+        $classMetadataFactory = new ClassMetadataFactory(new AttributeLoader());
+        $discriminator = new ClassDiscriminatorFromClassMetadata($classMetadataFactory);
+        $normalizer = new PropertyNormalizer($classMetadataFactory, null, null, $discriminator);
+
+        $obj = $normalizer->denormalize(
+            ['type' => 'one'],
+            PropertyDummyInterface::class,
+            null,
+            [AbstractNormalizer::ALLOW_EXTRA_ATTRIBUTES => false]
+        );
+
+        $this->assertInstanceOf(PropertyDiscriminatedDummyOne::class, $obj);
+    }
 }
 
 class PropertyDummy