Compliance Impact

This vulnerability allows unauthorized access to sensitive data by bypassing protected fields and object-level access controls in Parse Server. Specifically, it enables unauthenticated clients to enumerate objects linked through protected relations, such as private group memberships, block lists, or account-to-resource associations, without proper authorization.

Such unauthorized data exposure can lead to violations of data privacy and security requirements mandated by common standards and regulations like GDPR and HIPAA, which require strict controls on access to personal and sensitive information.

Therefore, applications relying on Parse Server versions affected by this vulnerability may face compliance risks due to potential unauthorized disclosure of protected data.

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Executive Summary

CVE-2026-53726 is a security vulnerability in Parse Server where the $relatedTo query operator could bypass protectedFields and owning-object Access Control List (ACL) restrictions.

This means that an unauthenticated client, with only public API credentials and knowledge of an object's objectId, could read the membership of a Relation field even if that field was hidden or the owning object was not readable by the client.

As a result, unauthorized users could enumerate objects linked through protected relations, such as private group memberships or block lists, without needing a user session, master key, or Cloud Code access.

The vulnerability was patched in Parse Server versions 8.6.80 and 9.9.1-alpha.6 by enforcing proper authorization checks on $relatedTo queries.

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Impact Analysis

This vulnerability can lead to unauthorized disclosure of sensitive data by allowing unauthenticated users to access relation memberships that should be protected.

• Exposure of private group memberships.
• Leakage of block lists.
• Disclosure of account-to-resource associations that rely on protected Relation fields.

Because the attack requires only public API credentials and knowledge of an objectId, it can be exploited remotely with low complexity, potentially compromising confidentiality of protected data.

There is no complete workaround other than upgrading to patched versions; mitigation can include avoiding exposure of sensitive membership data or enforcing access controls in beforeFind triggers.

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Detection Guidance

This vulnerability involves unauthorized access through the Parse Server's $relatedTo query operator bypassing protectedFields and ACL restrictions. Detection would involve monitoring for unusual or unauthorized $relatedTo queries that access relation memberships without proper authentication.

Since the vulnerability can be exploited by unauthenticated clients using only public API credentials and knowledge of objectIds, detection could include logging and analyzing API requests for $relatedTo queries that return data from protected relations or objects that should be inaccessible.

Specific commands are not provided in the resources, but general approaches include enabling detailed request logging on the Parse Server and searching logs for $relatedTo queries, especially those that do not have accompanying user session tokens or master keys.

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Mitigation Strategies

The primary and recommended mitigation is to upgrade Parse Server to version 8.6.80 or later, or 9.9.1-alpha.6 or later, where the vulnerability has been patched.

If immediate upgrading is not possible, applications can mitigate the risk by avoiding exposure of sensitive membership information through Relation fields or by enforcing access control in beforeFind triggers to restrict unauthorized queries.

No complete workaround exists other than upgrading, so prioritizing the update is critical to prevent unauthorized data exposure.

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