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GHSA-9rjg-x2p2-h68h

MEDIUM

GHSA-9rjg-x2p2-h68h is a medium-severity (CVSS 6.5) CWE-843 vulnerability in api-platform/core. O3 Security confirms whether GHSA-9rjg-x2p2-h68h is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

API Platform Core: Relation IRIs are not type-checked: a related resource can be denormalised as the wrong resource type (type confusion)

Also known asCVE-2026-54164
Published
Aug 7, 2026
Updated
Aug 7, 2026
Affected
3 pkgs
Patched
3 / 3
Exploits
None indexed

Blast Radius

3 pkgs affected
🐘api-platform/core🐘api-platform/core🐘api-platform/core

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

Summary

The API Platform serializer's AbstractItemNormalizer does not validate the resource type returned when resolving relation IRIs, allowing type confusion where a resource of an unintended type can be silently assigned to a relation property.

Impact

An attacker who can submit write requests (POST/PUT/PATCH) to an API Platform endpoint with writable relations can supply a relation IRI pointing to a resource of a different type than the relation's declared class. Because getResourceFromIri() does not pass an $operation to IriConverter::getResourceFromIri(), the is_a type guard at IriConverter.php:86 is skipped. For untyped relation properties (legacy @var-only style), the wrong-typed object is silently assigned, corrupting invariants and potentially feeding downstream logic that assumes the declared type (CWE-843). For typed properties (modern PHP 8.x), the substitution is blocked by Symfony's PropertyAccessor with an InvalidTypeException.

Affected versions

  • api-platform/core < 4.1.30
  • api-platform/core >= 4.2.0, < 4.2.26
  • api-platform/core >= 4.3.0, < 4.3.12

Older major series (2.x, 3.x) ship the same vulnerable code path and are end-of-life; no fix is planned.

Patched versions

  • 4.1.30
  • 4.2.26
  • 4.3.12

Fix

An is_a guard is added inside AbstractItemNormalizer::getResourceFromIri() (and the equivalent inline call sites on 4.1) so that a mismatched IRI throws InvalidArgumentException, mirroring the operation-aware check the IriConverter already performs when an operation is supplied. This forces a 400 Bad Request response for cross-type IRIs instead of a silent assignment.

Workarounds

Declare a PHP type on every writable relation property (e.g. public ?Foo $relation = null; instead of @var Foo $relation). Symfony's PropertyAccessor will then reject a mismatched object with InvalidTypeException. This does not cover collections of mixed-type interfaces; upgrading to a patched version is the only complete fix.

Proof of concept

A functional test posts a Bar IRI to a Foo-declared relation on an untyped property. Without the fix the server responds with HTTP 201 and the Bar IRI appears in the response payload. With the fix the server responds with HTTP 400 (Invalid IRI "/bars/1").

Full PoC: tests/Functional/Security/TypeConfusionRelationIriTest.php in the patched branches.

References

  • src/Serializer/AbstractItemNormalizer.php — vulnerable relation IRI load
  • src/Symfony/Routing/IriConverter.php — conditional is_a guard (operation-aware path)

Credit

Reported by @alexandre-daubois.

Affected Packages

3 total 3 fixed
EcosystemPackageVulnerable rangeFix
🐘Packagistapi-platform/coreall versions4.1.30
🐘Packagistapi-platform/core≥ 4.2.0&&< 4.2.264.2.26
🐘Packagistapi-platform/core≥ 4.3.0&&< 4.3.124.3.12

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for api-platform/core. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

  2. Fix

    Update api-platform/core to 4.1.30 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-9rjg-x2p2-h68h is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 pinpoints whether GHSA-9rjg-x2p2-h68h is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-9rjg-x2p2-h68h. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

## Summary The API Platform serializer's `AbstractItemNormalizer` does not validate the resource type returned when resolving relation IRIs, allowing type confusion where a resource of an unintended type can be silently assigned to a relation property. ## Impact An attacker who can submit write requests (POST/PUT/PATCH) to an API Platform endpoint with writable relations can supply a relation IRI pointing to a resource of a different type than the relation's declared class. Because `getResourceFromIri()` does not pass an `$operation` to `IriConverter::getResourceFromIri()`, the `is_a` type
O3 Security · Impact-Aware SCA

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