CVE-2026-93758 in Mongoid
Summary
by MITRE • 09/18/2026
An insecure direct object reference in the nested attributes handling of the Mongoid object-document mapper may allow a user with basic application privileges to reference a record identifier that is not their own. Processing such a request can cause that record to be looked up without the usual ownership or scoping restrictions, then updated and linked to the requesting user's own record. This may result in unintended disclosure and unauthorized modification of data belonging to other users of the application.
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Analysis
by VulDB Data Team • 09/18/2026
The vulnerability described constitutes an Insecure Direct Object Reference (IDOR), a critical web security flaw categorized under CWE-639 within the Common Weakness Enumeration framework. This issue arises specifically from how the Mongoid object-document mapper processes nested attributes during data updates. When an application accepts user input to update records, it relies on identifiers provided in that input to locate specific database entries. In this scenario, the security mechanism fails to validate whether the requesting user has legitimate ownership or administrative privileges over the target record identifier before processing the modification request. This lack of authorization checks allows a malicious actor with basic application privileges to manipulate object references directly, bypassing intended access controls and interacting with resources belonging to other users.
From an operational perspective, this flaw enables unauthorized data disclosure and modification. By supplying a record identifier that belongs to another user, an attacker can trigger the backend logic to retrieve and update that external record as if it were their own. This results in the unintended exposure of sensitive information associated with victim accounts, such as personal details or private communications. Furthermore, because the vulnerability allows for updates linked to the requesting user's account, attackers can corrupt data integrity by altering records they do not own. This dual impact compromises both confidentiality and integrity, which are core pillars of the CIA triad in information security. The ability to link external records to a controlled account may also facilitate further attacks, such as privilege escalation or lateral movement within the application ecosystem if those linked records influence access decisions elsewhere.
The technical root cause lies in the configuration or implementation of nested attribute handling within Mongoid. Typically, frameworks like Mongoid provide mechanisms for mass assignment and association management that can be exploited if not properly constrained. The vulnerability suggests that the framework is accepting user-supplied identifiers for associated objects without performing a secondary authorization check against the current session's context. This aligns with MITRE ATT&CK technique T1078, Valid Accounts, as it leverages legitimate but insufficiently privileged credentials to perform actions outside their scope. It also reflects patterns seen in CWE-269, Improper Privilege Management, where the application fails to enforce role-based or ownership-based restrictions during critical data operations.
To mitigate this vulnerability, developers must implement strict authorization checks at the point of object retrieval and update. This involves verifying that the current user owns the record being modified or possesses explicit administrative rights before allowing any changes via nested attributes. Framework-specific configurations should be reviewed to ensure that mass assignment protections are enabled and that only whitelisted fields can be updated through bulk operations. Additionally, implementing indirect reference maps where internal database IDs are replaced with opaque, non-sequential identifiers in the API layer can reduce the risk of enumeration attacks, although this is a defense-in-depth measure rather than a substitute for proper authorization logic. Regular security testing, including automated static analysis and dynamic penetration testing focused on IDOR scenarios, should be integrated into the development lifecycle to detect such flaws early.