CVE-2026-57481 in parse-server
Summary
by MITRE • 07/09/2026
Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to 9.9.1-alpha.13 and 8.6.83, a LiveQuery subscriber could receive object field values they were not authorized to read when a single save changed both an object field and the subscriber's ACL read access, because leave and enter events included the wrong object state. This issue is fixed in versions 9.9.1-alpha.13 and 8.6.83.
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Analysis
by VulDB Data Team • 07/09/2026
This vulnerability affects Parse Server, a popular open source backend solution that runs on Node.js infrastructure. The security flaw exists in versions prior to 9.9.1-alpha.13 and 8.6.83, specifically targeting the LiveQuery functionality that enables real-time object synchronization for connected clients. The issue stems from improper access control handling during concurrent operations where a single save operation simultaneously modifies both an object field and the subscriber's access control list permissions.
The technical implementation flaw occurs within the LiveQuery subscription mechanism when processing leave and enter events. When a save operation modifies both an object's field values and a subscriber's ACL read permissions, the system incorrectly includes outdated object state information in the event notifications. This creates a scenario where unauthorized users can receive field values they should not have access to, as the system fails to properly validate access controls during the transition period between the old and new object states.
The operational impact of this vulnerability is significant for applications relying on Parse Server's real-time capabilities. Attackers could potentially exploit this weakness to gain unauthorized access to sensitive data fields that are normally protected by access control lists. The issue particularly affects multi-user environments where different users have varying permission levels, as it creates a window where object state information flows to subscribers who should not have access to certain fields due to permission changes occurring within the same transaction.
This vulnerability can be categorized under CWE-284 Access Control Issues and aligns with ATT&CK technique T1078 Valid Accounts, as it exploits legitimate user permissions to access unauthorized data through a timing window in the access control validation process. The flaw represents a privilege escalation vector where a user with read access to an object can potentially obtain additional field-level information that should be restricted based on their current ACL permissions.
The fix implemented in versions 9.9.1-alpha.13 and 8.6.83 addresses this issue by ensuring proper state management during concurrent save operations. The updated code now correctly validates access controls for all object fields included in leave and enter events, preventing unauthorized information disclosure. Organizations should immediately upgrade to these patched versions to eliminate the risk of unauthorized data exposure through the LiveQuery functionality.
Security practitioners should implement additional monitoring for LiveQuery operations and access control changes to detect any potential exploitation attempts. The vulnerability underscores the importance of proper state validation in real-time systems and highlights the need for comprehensive testing of concurrent operations involving access control modifications. This issue serves as a reminder that real-time data synchronization mechanisms require careful attention to access control boundaries, particularly when dealing with atomic operations that modify both data content and permission structures simultaneously.