parse-server: Relation `$relatedTo` query bypasses `protectedFields` and owning-object ACL

### 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.

Source published

19 Jun 2026 19:35:19 UTC

Source modified

19 Jun 2026 19:56:04 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

Publisher rating · MODERATE