CVE-2026-97193 in Secure Custom Fields Plugin
Summary
by MITRE • 11/08/2026
The Secure Custom Fields WordPress plugin before 6.9.8 does not verify that a user is allowed to edit the target object before writing to it during bidirectional relationship synchronization, allowing users with contributor-level access and above to add or remove a reference to their own object on arbitrary posts, users, or terms they cannot otherwise edit.
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Analysis
by VulDB Data Team • 11/08/2026
The vulnerability identified in Secure Custom Fields versions prior to 6.9.8 represents a critical failure in authorization logic within the plugin's bidirectional relationship synchronization mechanism. This flaw stems from an insufficient verification of user permissions when processing updates to custom field relationships. Specifically, during the operation where references are added or removed between objects such as posts, users, or terms, the software fails to validate whether the initiating actor possesses the necessary administrative privileges for the target object being modified. Instead, the system relies on a flawed assumption that if a user can access the relationship interface, they inherently have permission to alter the underlying data structures associated with those relationships. This architectural oversight allows an attacker who has authenticated as a contributor or higher-level role to bypass standard content restrictions and manipulate metadata for resources outside their authorized scope.
From a technical perspective, this issue is classified under CWE-269, which denotes Improper Privilege Control. The root cause lies in the application logic handling bidirectional updates, where the write operation proceeds without checking if the current user has edit capabilities on the specific post ID, user ID, or term taxonomy being referenced. In a properly secured implementation, every modification to an object's metadata should trigger a secondary authorization check against the target resource itself, not just the relationship field. By omitting this step, the plugin effectively treats all authenticated users with basic editing rights as administrators for any custom field relationships they can interact with in the user interface. This creates a direct path for unauthorized data manipulation that exploits the trust placed in the frontend interaction model without corresponding backend validation.
The operational impact of this vulnerability is significant because it enables privilege escalation and data integrity compromise within WordPress environments. An attacker leveraging contributor-level access or higher could inject malicious references into arbitrary posts, potentially altering site structure or displaying unintended content to other users. Furthermore, by adding or removing relationships on user objects, an attacker might disrupt user association logic used for membership plugins or custom workflows. For term taxonomy entries, this could lead to incorrect categorization of content across the entire website. Since bidirectional synchronization implies that changes in one direction automatically update the reverse link, a single malicious action can propagate inconsistencies throughout multiple data entities, degrading site reliability and potentially exposing sensitive associations between users and specific pieces of content or categories.
This behavior aligns with MITRE ATT&CK technique T1078, Valid Accounts, as it requires initial authentication but exploits weak access control to perform actions beyond the user's assigned role. It also reflects aspects of CWE-928, Privilege Misassignment, where permissions are incorrectly granted during runtime operations due to flawed logic rather than static configuration errors. The vulnerability highlights a common pitfall in plugin development where convenience features like automatic bidirectional syncing are implemented without rigorous security auditing of the underlying permission checks.
To mitigate this risk, administrators must immediately upgrade Secure Custom Fields to version 6.9.8 or later, which addresses these authorization gaps by implementing strict capability verification for both source and target objects during relationship updates. Until an update is applied, site owners should consider restricting access to custom field editing interfaces through additional security plugins that enforce granular role-based permissions at the meta key level. Additionally, auditing user roles to ensure only trusted administrators have contributor-level or higher privileges can reduce the attack surface for this specific exploitation vector. Regular monitoring of database integrity and relationship tables may also help detect any unauthorized modifications resulting from successful exploits prior to patching.