Executive Summary

CVE-2026-30850 is a moderate severity vulnerability affecting Parse Server versions prior to 8.6.9 and between 9.0.0 and 9.5.0-alpha.9. The vulnerability exists in the file metadata endpoint (`GET /files/:appId/metadata/:filename`), which does not enforce the `beforeFind` and `afterFind` triggers used for access control on file metadata.

Because these triggers are bypassed, unauthorized users can access file metadata without proper permissions. This metadata includes user-defined key-value pairs added via `addMetadata`. However, the actual file content remains protected and inaccessible.

The issue arises from missing authorization checks on the metadata endpoint, allowing attackers to retrieve metadata over the network with low complexity and no user interaction.

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Impact Analysis

This vulnerability can lead to unauthorized disclosure of file metadata in Parse Server deployments that rely on `beforeFind` and `afterFind` triggers for access control.

Attackers can exploit this flaw to access sensitive metadata information without any privileges or user interaction, potentially exposing confidential or private data stored as metadata.

Although the actual file contents remain secure, the exposure of metadata could lead to information leakage, which might be leveraged for further attacks or privacy violations.

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Compliance Impact

I don't know

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Detection Guidance

This vulnerability can be detected by attempting to access the file metadata endpoint without proper authorization and observing if the beforeFind and afterFind triggers are enforced.

A practical way to test this is to send an HTTP GET request to the endpoint `/files/:appId/metadata/:filename` on your Parse Server deployment and check if unauthorized access to file metadata is possible.

For example, you can use the following curl command to test access:

• curl -i http://your-parse-server-domain/files/yourAppId/metadata/yourFilename

If the server returns metadata without enforcing access controls (i.e., without a 403 Forbidden response when unauthorized), it indicates the vulnerability is present.

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Mitigation Strategies

The immediate mitigation step is to upgrade your Parse Server to version 8.6.9 or later, or 9.5.0-alpha.9 or later, where the vulnerability has been patched.

If upgrading is not immediately possible, you can temporarily disable the vulnerable metadata endpoint by overriding its route with middleware that rejects all requests, for example by responding with HTTP 403 Forbidden.

This workaround prevents unauthorized access to file metadata until the official patch can be applied.

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