# CVE-2026-122053: Symfony Serializer ObjectNormalizer property traversal bypass

Source: https://junglewise.ai/threats/cve-2026-122053-the-symfony-serializer-component-objectnormalizer-treats-any  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-06. Updated: 2026-11-06  
License: CC BY 4.0 with a link back

CVE-2026-122053 · Severity: info · Published 2026-11-06

Symfony's Serializer component allows attackers to modify nested object properties through specially crafted input containing dot notation or bracket syntax. Applications that process untrusted input—such as web forms or API requests—can have their internal object state altered, bypassing security metadata and potentially leading to privilege escalation or unauthorized data modification.

Vendors: [Symfony](https://junglewise.ai/threats/vendors/symfony).

## Quick answers

**Is CVE-2026-122053 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-122053 being exploited in the wild.

**How severe is CVE-2026-122053?** Informational severity, published 6 November 2026.

**Which products and versions are affected?** Symfony Serializer component 5.4.41–5.4.55, 6.4.9–6.4.49, 7.0.9–7.1.1, 7.1.2–7.4.22, 8.x–8.1.10.

**Is there a fix for CVE-2026-122053?** Yes: fixed in 5.4.56, 6.4.50, 7.1.0, 7.4.23, 8.1.11. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-122053 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-122053?** Check whether you run Symfony Serializer component at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in 5.4.56, 6.4.50, 7.1.0, 7.4.23, 8.1.11

## Technical details

The ObjectNormalizer component treats attribute names containing dots or brackets as property paths rather than literal attribute names, passing them directly to PropertyAccessor::setValue() which traverses the object graph. An attacker can craft payloads like "customer.admin" to write to nested objects, and can invoke public methods if a path segment matches a method name. The #[Ignore] metadata attribute and security restrictions are bypassed when objects are accessed through these paths rather than denormalized directly, and with OBJECT_TO_POPULATE mode the modifications can be persisted to the database.

## Affected products

- Symfony Serializer component 5.4.41–5.4.55, 6.4.9–6.4.49, 7.0.9–7.1.1, 7.1.2–7.4.22, 8.x–8.1.10

## Timeline

- 2026-11-06: disclosed

## Related threats

- [Symfony Serializer arbitrary file handling via DataUriNormalizer](https://junglewise.ai/threats/cve-2026-118515-the-symfony-serializer-component-dataurinormalizer-handles-only)