CVE-2026-122053
Received
Received - Intake
ObjectNormalizer Property Path Bypass in Symfony
Vulnerability report for CVE-2026-122053, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-11-06
Last updated on: 2026-11-06
Assigner: Checkmarx
Description
Description
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 traversal reaches an already hydrated entity graph, and the modified field may be persisted.
The fix accepts a property path only when the class metadata declares an attribute of that exact name. Declared paths keep working unchanged, and a path in the payload with no matching declaration is ignored.
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| symfony | serializer | From 5.4.41 (inc) to 5.4.56 (exc) |
| symfony | serializer | From 6.4.9 (inc) to 6.4.50 (exc) |
| symfony | serializer | From 7.0.9 (inc) to 7.1.0 (exc) |
| symfony | serializer | From 7.1.2 (inc) to 7.4.23 (exc) |
| symfony | serializer | From 8 (inc) to 8.1.11 (exc) |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-915 | The product receives input from an upstream component that specifies multiple attributes, properties, or fields that are to be initialized or updated in an object, but it does not properly control which attributes can be modified. |
