The Symfony Serializer component ObjectNormalizer treats any attribute name containing . (and, from Symfony 6.4, [) as a writable property path, allowing untrusted input to modify properties of nested objects and bypass their #[Ignore] metadata attribute in Symfony versions 5.4.41 prior to 5.4.56, 6.4.9 prior to 6.4.50, 7.0.9 prior to 7.1.0, 7.1.2 prior to 7.4.23, and 8.x prior to 8.1.11. ObjectNormalizer::isAllowedAttribute() accepts such names, and setAttributeValue() hands the name straight to PropertyAccessor::setValue(), which parses it as a property path and traverses into the nested object. A payload key such as customer.admin writes to $order->customer->admin. The #[Ignore] metadata attribute is only consulted when the nested object is denormalized in its own right, never when it is reached through a path. #[Groups] restrictions are not bypassed: the path is only accepted when no groups are passed in the context, and then groups restrict nothing. When the root class carries neither #[Ignore] nor #[Groups], no allowlist applies and every key of the payload is let through. Because PropertyAccessor also resolves a path segment against public methods, a segment matching a public method name invokes that method with the attacker’s value.Applications that bind untrusted input to objects are affected, including controllers using #[MapRequestPayload] or #[MapQueryString], whose default normalizer is ObjectNormalizer. With OBJECT_TO_POPULATE, as used for partial updates, the…

Affected: Ubuntu:16.04:LTS: symfony, Ubuntu:Pro:18.04:LTS: symfony, Ubuntu:Pro:20.04:LTS: symfony, Ubuntu:Pro:22.04:LTS: symfony, Ubuntu:Pro:24.04:LTS: symfony, Ubuntu:26.10: symfony, Ubuntu:26.04:LTS: symfony

The Symfony Serializer component ObjectNormalizer treats any attribute name containing . (and, from Symfony 6.4, [) as a writable property path, allowing untrusted input to modify properties of nested objects and bypass their #[Ignore] metadata attribute in Symfony versions 5.4.41 prior to 5.4.56, 6.4.9 prior to 6.4.50, 7.0.9 prior to 7.1.0, 7.1.2 prior to 7.4.23, and 8.x prior to 8.1.11. ObjectNormalizer::isAllowedAttribute() accepts such names, and setAttributeValue() hands the name straight to PropertyAccessor::setValue(), which parses it as a property path and traverses into the nested object. A payload key such as customer.admin writes to $order->customer->admin. The #[Ignore] metadata attribute is only consulted when the nested object is denormalized in its own right, never when it is reached through a path. #[Groups] restrictions are not bypassed: the path is only accepted when no groups are passed in the context, and then groups restrict nothing. When the root class carries neither #[Ignore] nor #[Groups], no allowlist applies and every key of the payload is let through. Because PropertyAccessor also resolves a path segment against public methods, a segment matching a public method name invokes that method with the attacker’s value.Applications that bind untrusted input to objects are affected, including controllers using #[MapRequestPayload] or #[MapQueryString], whose default normalizer is ObjectNormalizer. With OBJECT_TO_POPULATE, as used for partial updates, the…