Compliance Impact

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Executive Summary

[{'type': 'paragraph', 'content': "CVE-2026-32594 is a security vulnerability in Parse Server's GraphQL WebSocket endpoint used for subscriptions. This endpoint bypassed the Express middleware chain that normally enforces authentication, introspection control, and query complexity limits. As a result, an attacker could connect to this WebSocket endpoint without providing valid application or API keys, access the GraphQL schema even when introspection was disabled, and send arbitrarily complex queries that bypass configured limits."}, {'type': 'paragraph', 'content': 'The root cause was that the WebSocket subscription feature was incomplete and did not enforce the necessary security middleware. The vulnerability was fixed by removing the WebSocket subscription support entirely, including the removal of the `subscriptions-transport-ws` package and related code, ensuring all GraphQL operations are subject to proper authentication and authorization checks.'}] [1, 2, 3]

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Impact Analysis

This vulnerability allows an attacker to bypass authentication and authorization controls by connecting to the GraphQL WebSocket endpoint without valid credentials. This can lead to unauthorized execution of GraphQL operations, exposure of the GraphQL schema through introspection even when it is supposed to be disabled, and the ability to send complex queries that exceed configured limits.

Such unauthorized access can result in information disclosure, potential resource exhaustion due to complex queries, and overall compromise of the security posture of the backend system running Parse Server.

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Detection Guidance

[{'type': 'paragraph', 'content': 'This vulnerability involves the GraphQL WebSocket endpoint at the path `/subscriptions` bypassing security middleware, allowing unauthorized access. Detection can focus on monitoring or blocking WebSocket upgrade requests to this endpoint.'}, {'type': 'paragraph', 'content': 'A practical detection method is to check for active WebSocket connections or upgrade requests targeting the `/subscriptions` path on your Parse Server instance.'}, {'type': 'list_item', 'content': 'Use network monitoring tools like tcpdump or Wireshark to filter WebSocket upgrade requests to the `/subscriptions` endpoint.'}, {'type': 'list_item', 'content': 'Example tcpdump command to capture WebSocket upgrade requests on port 80 or 443 (adjust port as needed):'}, {'type': 'list_item', 'content': "tcpdump -i any -A 'tcp port 80 or tcp port 443' | grep -i 'GET /subscriptions HTTP/1.1'"}, {'type': 'list_item', 'content': 'Check server logs for incoming WebSocket upgrade requests to `/subscriptions` that do not require authentication.'}, {'type': 'list_item', 'content': 'If using a reverse proxy (e.g., Nginx), enable access logging and filter for requests to `/subscriptions` with `Upgrade: websocket` headers.'}, {'type': 'paragraph', 'content': 'Since the vulnerability allows bypassing authentication, any unauthorized WebSocket connection to `/subscriptions` indicates exposure.'}] [3]

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Mitigation Strategies

The primary mitigation is to upgrade Parse Server to a patched version where the vulnerability is fixed: version 8.6.40 or 9.6.0-alpha.14 or later.

If immediate upgrade is not possible, a recommended workaround is to block WebSocket upgrade requests to the `/subscriptions` endpoint at the network level.

• Configure your reverse proxy or firewall to deny or drop WebSocket upgrade requests targeting `/subscriptions`.
• Remove or disable the GraphQL WebSocket subscription feature in your Parse Server configuration if feasible.

These steps prevent attackers from exploiting the bypass by disallowing unauthorized WebSocket connections that circumvent middleware authentication.

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