---
id: CVE-2026-53726
title: >-
  parse-server: Relation `$relatedTo` query bypasses `protectedFields` and
  owning-object ACL
summary: >-
  parse-server: Relation `$relatedTo` query bypasses `protectedFields` and
  owning-object ACL
severity: medium
cwe:
  - CWE-639
vendor: parse-server
product: parse-server
affected:
  - 'parse-server >= 9.0.0, < 9.9.1-alpha.6'
  - parse-server < 8.6.80
patched:
  - parse-server 9.9.1-alpha.6
  - parse-server 8.6.80
published: '2026-06-19'
updated: '2026-06-19'
source: GHSA
sourceUrl: 'https://github.com/advisories/GHSA-wmwx-jr2p-4j4r'
references:
  - url: >-
      https://github.com/parse-community/parse-server/security/advisories/GHSA-wmwx-jr2p-4j4r
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-53726'
  - url: 'https://github.com/parse-community/parse-server/pull/10493'
  - url: 'https://github.com/parse-community/parse-server/pull/10494'
  - url: 'https://github.com/advisories/GHSA-wmwx-jr2p-4j4r'
tags:
  - ghsa
  - npm
epss: 0.0048
epssPercentile: 0.38932
ingestedAt: '2026-06-22T15:52:21.057Z'
ecosystem: npm
---

## Overview

### Impact

A relation query using the `$relatedTo` operator could read the membership of a `Relation` field even when that field was hidden from the requesting client by `protectedFields`, and even when the object owning the relation was not readable by the client under its ACL or class-level permissions. The request requires only the public API credentials that Parse clients normally carry — no user session, master key, or Cloud Code is needed.

As a result, an unauthenticated client who knows or obtains the owning object's `objectId` could enumerate the objects linked through a protected relation, or combine the operator with an `objectId` constraint to use it as a membership oracle — confirming whether a specific object is linked to a private parent. This affects applications that rely on `protectedFields` or object ACLs to keep `Relation` membership confidential, such as private group memberships, block lists, or account-to-resource associations.

### Patches

The relation query path now authorizes `$relatedTo` against the owning object before reading the relation join table, using the caller's authentication context. The relation key is checked against the owning class's `protectedFields` (the query is rejected if the key is protected), and the owning object must be readable by the caller under its class-level permissions, ACL, and pointer permissions; otherwise the relation returns no results. Master and maintenance requests are unaffected. The check is applied consistently whether `$relatedTo` is used at the top level or nested within `$or`, `$and`, or `$nor`.

### Workarounds

There is no complete workaround without upgrading. As mitigation, applications can avoid exposing sensitive membership through `Relation` fields to untrusted clients, or enforce access on the queried class in a `beforeFind` trigger.

## Affected packages

- `parse-server >= 9.0.0, < 9.9.1-alpha.6`
- `parse-server < 8.6.80`

## Remediation

Upgrade to a patched release:

- `parse-server 9.9.1-alpha.6`
- `parse-server 8.6.80`