Parse Server Denial of Service via Nested Query Operators

Compliance Impact

CVE-2026-57480 is a denial of service (DoS) vulnerability in Parse Server that allows attackers to cause exponential-time processing of deeply nested query operators, leading to server unavailability.

While the vulnerability primarily impacts service availability by blocking the Node.js event loop and making the server unresponsive, it does not directly involve unauthorized access to sensitive data or data breaches.

However, disruption of service availability can indirectly affect compliance with standards like GDPR and HIPAA, which require ensuring availability and resilience of systems processing personal or protected health information.

Organizations relying on Parse Server must address this vulnerability promptly to maintain compliance with such regulations by preventing denial of service incidents that could impact data availability and service continuity.

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Executive Summary

This vulnerability exists in Parse Server versions prior to 9.9.1-alpha.12 and 8.6.82. It involves the handling of deeply nested $or, $and, and $nor query condition operators in the REST API or LiveQuery query processing. When such deeply nested queries are processed, they can cause exponential-time processing in the internal query-traversal helper, which in turn blocks the Node.js event loop.

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Impact Analysis

The vulnerability can cause the Node.js event loop to be blocked due to exponential-time processing of certain deeply nested queries. This can lead to denial of service conditions where the backend becomes unresponsive or significantly slowed down, impacting the availability and performance of applications relying on Parse Server.

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Mitigation Strategies

To mitigate this vulnerability, upgrade Parse Server to version 9.9.1-alpha.12 or later, or version 8.6.82 or later.

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Detection Guidance

This vulnerability can be detected by monitoring for unusually high CPU usage or blocked Node.js event loops on Parse Server instances when processing queries. Specifically, look for requests containing deeply nested logical operators such as $or, $and, and $nor in the REST API or LiveQuery queries.

To detect potential exploitation attempts, you can log and analyze incoming queries for deeply nested logical operators that exceed normal depth limits.

While there are no specific built-in commands provided in the resources, you can use network monitoring and logging tools to capture and inspect query payloads for deeply nested logical operators.

For example, you might use tools like tcpdump or Wireshark to capture HTTP traffic to the Parse Server and then grep or parse the payloads for occurrences of $or, $and, or $nor with deep nesting.

• Use tcpdump to capture traffic on the Parse Server port (e.g., 1337): tcpdump -i eth0 -s 0 -w parse_traffic.pcap port 1337
• Analyze captured traffic with tshark or Wireshark to extract HTTP POST requests containing query payloads.
• Use jq or similar JSON parsing tools to inspect the query JSON for deeply nested $or, $and, or $nor operators.
• Monitor server logs for slow query processing times or errors related to query depth limits.

Ultimately, upgrading to the fixed versions (9.9.1-alpha.12 or 8.6.82) is strongly recommended to prevent this vulnerability.

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