{"id":"CVE-2026-53726","aliases":["BIT-parse-2026-53726","GHSA-wmwx-jr2p-4j4r"],"url":"https://o3.security/vulnerability/CVE-2026-53726","summary":"Parse Server: Relation `$relatedTo` query bypasses `protectedFields` and owning-object ACL","details":"### Impact\n\nA relation query using the `$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.\n\nAs 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.\n\n### Patches\n\nThe 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`.\n\n### Workarounds\n\nThere 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.","published":"2026-06-12T18:37:01.695Z","modified":"2026-10-21T02:58:30.139449108Z","cvss":null,"epss":{"score":0.00276,"percentile":0.20183,"asOf":"2026-09-17"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"parse-server","fixedVersion":"9.9.1-alpha.6"},{"ecosystem":"npm","name":"parse-server","fixedVersion":"8.6.80"}],"fix":{"url":"https://github.com/parse-community/parse-server/pull/10493","label":"parse-community/parse-server#10493"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53726.json"},{"type":"ADVISORY","url":"https://github.com/parse-community/parse-server/security/advisories/GHSA-wmwx-jr2p-4j4r"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-53726"},{"type":"FIX","url":"https://github.com/parse-community/parse-server/pull/10493"},{"type":"FIX","url":"https://github.com/parse-community/parse-server/pull/10494"},{"type":"PACKAGE","url":"https://github.com/parse-community/parse-server"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-21T02:58:30.139449108Z"}}