CVE-2026-33538 in parse-server
Summary
by MITRE • 03/24/2026
Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to versions 8.6.58 and 9.6.0-alpha.52, an unauthenticated attacker can cause denial of service by sending authentication requests with arbitrary, unconfigured provider names. The server executes a database query for each unconfigured provider before rejecting the request, and since no database index exists for unconfigured providers, each request triggers a full collection scan on the user database. This can be parallelized to saturate database resources. This issue has been patched in versions 8.6.58 and 9.6.0-alpha.52.
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Analysis
by VulDB Data Team • 03/29/2026
The vulnerability described in CVE-2026-33538 affects Parse Server, a popular open-source backend infrastructure designed for deployment on Node.js environments. This issue represents a significant denial of service weakness that can be exploited by unauthenticated attackers without requiring any prior authentication credentials or privileged access to the system. The vulnerability specifically targets the authentication handling mechanism within the Parse Server framework, creating a condition where malicious actors can systematically consume system resources through carefully crafted requests. The flaw exists in versions prior to 8.6.58 and 9.6.0-alpha.52, indicating that this represents a long-standing issue within the software's authentication processing logic.
The technical root cause of this vulnerability lies in the server's handling of authentication requests with unconfigured provider names. When an attacker sends an authentication request containing an arbitrary provider name that has not been configured within the system, the Parse Server processes each request by executing a database query for every unconfigured provider. This behavior demonstrates a fundamental flaw in the system's resource management and query optimization, as the server fails to implement proper early validation or filtering mechanisms. The absence of database indexes specifically designed for unconfigured providers creates a scenario where each authentication attempt triggers a full collection scan against the user database, effectively turning what should be a simple validation check into an expensive database operation.
The operational impact of this vulnerability is severe and directly translates to resource exhaustion and system instability. Attackers can parallelize their requests to saturate database resources, creating a denial of service condition that affects legitimate users and system availability. This vulnerability can be exploited at scale to overwhelm database connections, CPU resources, and memory allocation, particularly in environments where the user database contains substantial amounts of data. The full collection scan behavior means that even a moderate number of parallel requests can cause significant performance degradation or complete system unresponsiveness, making this a critical concern for production environments that rely on Parse Server for backend services.
This vulnerability maps to CWE-400, which specifically addresses "Uncontrolled Resource Consumption" or "Resource Exhaustion" conditions in software systems. The issue also aligns with ATT&CK technique T1499.004, which covers "Endpoint Denial of Service" through resource exhaustion attacks. The exploitation pattern demonstrates how attackers can leverage application logic flaws to create cascading resource consumption effects that ultimately compromise system availability. Organizations should implement immediate mitigations including upgrading to patched versions 8.6.58 and 9.6.0-alpha.52, implementing rate limiting mechanisms for authentication requests, and establishing monitoring for unusual authentication request patterns. Database optimization should include creating appropriate indexes for provider validation checks, while network-level protections can help limit the impact of parallelized attack attempts. The vulnerability highlights the importance of proper input validation and early exit conditions in authentication systems to prevent unnecessary database operations that can be exploited for resource exhaustion attacks.