CVE-2026-105860 in payload
Summary
by MITRE • 10/06/2026
Payload is a free and open source headless content management system. In @payloadcms/plugin-multi-tenant versions before 3.90.0 and canary versions before 4.0.0-canary.34, the default tenant array field access allows an authenticated user to assign the user's own account to other tenants. Deployments that replace the default behavior with secured tenants arrayFieldAccess.create and tenants arrayFieldAccess.update functions are not affected by this behavior. This issue is fixed in versions 3.90.0 and 4.0.0-canary.34.
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Analysis
by VulDB Data Team • 10/06/2026
The vulnerability identified in Payload CMS plugin-multi-tenant prior to version 3.90.0 represents a critical authorization flaw within the headless content management system's multi-tenancy architecture. This issue stems from an insecure direct object reference mechanism where the default configuration for tenant array field access fails to enforce proper ownership validation during creation and update operations. Specifically, when an authenticated user interacts with the tenants endpoint, the underlying logic permits the assignment of any valid user account to a specific tenant context without verifying that the requesting user possesses administrative privileges or explicit permission to modify such assignments. This lack of server-side authorization checks allows malicious actors who have obtained legitimate credentials for lower-privilege accounts to escalate their influence within the multi-tenant environment by arbitrarily associating themselves with other tenants, thereby bypassing intended isolation boundaries between different organizational units or customer groups managed by the platform.
From a technical perspective, this flaw aligns closely with CWE-284 Improper Access Control and CWE-798 Use of Hard-coded Credentials if default configurations are exploited without modification. The vulnerability is particularly dangerous because it does not require complex exploitation techniques; rather, it relies on the fundamental absence of access control checks in the API handlers responsible for managing tenant-user relationships. In a typical multi-tenant SaaS deployment, strict separation of data and administrative rights between tenants is paramount to maintain confidentiality and integrity. By allowing an authenticated user to assign their own account to other tenants, the system effectively grants that user unauthorized visibility into or potential control over resources belonging to those other tenants. This can lead to severe operational impacts including data leakage across tenant boundaries, unauthorized modification of shared configurations, and potential lateral movement within the infrastructure if further privileges are derived from these cross-tenant associations.
The risk is significantly mitigated for deployments that have explicitly customized their security posture by replacing the default behavior with secured implementations of tenants arrayFieldAccess.create and tenants arrayFieldAccess.update functions. These custom access control functions allow administrators to define granular permissions, ensuring that only users with specific roles or higher privilege levels can modify tenant assignments. However, organizations relying on out-of-the-box configurations remain exposed until they apply the official patch. The vulnerability is resolved in version 3.90.0 for the stable release track and version 4.0.0-canary.34 for the development track, where the default access control logic has been hardened to enforce strict validation of user permissions before allowing any changes to tenant memberships.
To address this issue immediately, administrators should upgrade their payloadcms/plugin-multi-tenant dependency to at least version 3.90.0 or 4.0.0-canary.34 as soon as possible. For those unable to update immediately due to compatibility constraints with other system components, a temporary mitigation involves implementing custom access control functions that explicitly check for administrative privileges before allowing any modifications to the tenant array fields. This defensive coding approach ensures that even if the default logic remains vulnerable in older versions, the application layer enforces proper authorization policies consistent with industry best practices such as those outlined in OWASP Access Control Cheat Sheet. Regular auditing of API endpoints and continuous integration testing of access control rules are recommended to prevent similar privilege escalation vulnerabilities from being introduced or persisting in future updates.