CVE-2026-122301 in parse-server
Summary
by MITRE • 11/05/2026
Parse Server before 8.6.114 and 9.0.0 before 9.10.6-alpha.6 returns field values in object create responses to callers that lack read access to the created object through class-level permissions or the object's ACL. An attacker with create permission can create objects to obtain values set by Cloud Code triggers, schema defaults, and the class default ACL.
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Analysis
by VulDB Data Team • 11/05/2026
The vulnerability identified involves a critical information disclosure flaw within Parse Server versions prior to 8.6.114 and 9.0.0 before 9.10.6-alpha.6. This issue stems from an improper access control mechanism in the object creation response logic, specifically affecting how field values are returned to clients after an object is successfully created. Under normal security expectations, when a user creates an object with create permissions but lacks read permissions for that specific class or instance, they should not receive sensitive data associated with that object upon its creation. However, due to this flaw, the server erroneously includes all field values in the response payload sent back to the caller who initiated the write operation, regardless of their subsequent read access rights.
The technical root cause lies in the failure to filter out restricted fields from the response body during the post-creation phase. When a client submits data to create a new object, Parse Server processes various inputs including direct field values, default schema values, and those set by Cloud Code triggers or class-level Access Control Lists (ACLs). The system correctly enforces write permissions for creation but fails to apply read permission checks before serializing the resulting object into JSON format. Consequently, any data populated during this process becomes visible to the creator of the object, even if that user is explicitly denied read access by the application's security configuration. This behavior violates the principle of least privilege and creates a significant discrepancy between intended policy enforcement and actual runtime behavior.
The operational impact of this vulnerability allows an attacker with basic create permissions to perform unauthorized data exfiltration. By crafting specific requests, an adversary can trigger object creation events that populate sensitive fields via Cloud Code triggers or schema defaults. Since these values are returned in the response, the attacker gains access to internal application logic details, default configurations, and potentially secret keys or tokens managed by the class-level ACLs. This exposure facilitates further reconnaissance efforts, enabling attackers to map out the database structure, identify high-value targets for future attacks, and understand how security controls are implemented within the backend infrastructure. Such information leakage significantly lowers the barrier for subsequent exploitation attempts against more protected resources.
From a classification perspective, this vulnerability aligns with CWE-209, which describes an Information Exposure Through an Error Message, although it is broader as it involves structured data exposure rather than just error text. It also relates to CWE-863, concerning the improper enforcement of access control for read operations within write contexts. In terms of offensive security frameworks, this behavior supports techniques found in MITRE ATT&CK under Data from Local System or Discovery categories where an adversary gathers information about system configuration and data structures through legitimate but misconfigured API interactions. The flaw essentially turns a standard creation endpoint into a vector for sensitive data retrieval without requiring elevated privileges beyond initial write access.
To mitigate this risk, organizations must upgrade their Parse Server instances to version 8.6.114 or later, or specifically to version 9.10.6-alpha.6 and above where the patch has been applied. Until an upgrade is feasible, administrators should implement strict input validation and output filtering at the application layer if possible, ensuring that responses do not inadvertently leak internal state variables set by triggers or defaults. Additionally, reviewing class-level permissions to ensure that read access is explicitly denied for sensitive fields can help limit exposure, although relying solely on permission settings without patching remains risky due to this specific implementation flaw in the response serialization logic. Regular security audits and penetration testing should include checks for improper information disclosure during object creation workflows to detect similar misconfigurations early.