# CVE-2026-122053: Symfony: ObjectNormalizer Dotted-Key Property-Path Traversal Bypasses #[Ignore] on Nested Objects

Status: published. Published: 2026-11-06. Updated: 2026-11-06.

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.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: Checkmarx) — https://github.com/symfony/symfony/commit/fcaf87a93c7fa5b7fe9e9e8382d4ed0d0c52c67c
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: Checkmarx) — https://github.com/symfony/symfony/commit/9f7390678a255f7962fb1c81c42b26fa907d3437

## Affected products and versions

- sensiolabs / symfony (symfony/serializer): ≥ 5.4.41; < 5.4.56 (affected, git); ≥ 6.4.9; < 6.4.50 (affected, git); ≥ 7.0.9; < 7.1.0 (affected, git); ≥ 7.1.2; < 7.4.23 (affected, git); ≥ 8.0.0; < 8.1.11 (affected, git). Source: CNA: Checkmarx

## Severity and prioritization

- CVSS 4.0: 6.9 (medium); CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N; source: CNA: Checkmarx

- CVSS 3.1: 6.5 (medium); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N; source: ADP: CISA-ADP

- CVSS 4.0: 6.9 (medium); CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X; source: NVD: 596c5446-0ce5-4ba2-aa66-48b3b757a647

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: exploitation none; automatable yes; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-915

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/symfony/symfony/security/advisories/GHSA-hqp2-7rr8-hf26 (CNA: Checkmarx; third-party-advisory)

- https://github.com/symfony/symfony/commit/fcaf87a93c7fa5b7fe9e9e8382d4ed0d0c52c67c (CNA: Checkmarx; patch)

- https://github.com/symfony/symfony/commit/9f7390678a255f7962fb1c81c42b26fa907d3437 (CNA: Checkmarx; patch)

- https://github.com/symfony/symfony/commit/9f7390678a255f7962fb1c81c42b26fa907d3437 (596c5446-0ce5-4ba2-aa66-48b3b757a647)

- https://github.com/symfony/symfony/commit/fcaf87a93c7fa5b7fe9e9e8382d4ed0d0c52c67c (596c5446-0ce5-4ba2-aa66-48b3b757a647)

- https://github.com/symfony/symfony/security/advisories/GHSA-hqp2-7rr8-hf26 (596c5446-0ce5-4ba2-aa66-48b3b757a647)

## Provenance

- CNA: Checkmarx: https://www.cve.org/CVERecord?id=CVE-2026-122053; retrieved 2026-11-06; source updated 2026-11-06

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-122053; retrieved 2026-11-06; source updated 2026-11-06

Revision: d1f7673d6514fc2c129c226587f0ddb9e50b646fce57e8f995ad92ada6b82f5c

Canonical: https://y2.dev/cve/CVE-2026-122053

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