CVE-2026-91930 in Flowise
Summary
by MITRE • 09/15/2026
Flowise before 3.1.4 fails to scope enterprise organization and workspace membership APIs to the caller's tenant, allowing authenticated users to supply arbitrary organization IDs. Attackers can add themselves as organization owners, create workspaces, and gain administrative access to victim organizations by exploiting insufficient tenant isolation in the organizationuser and workspace endpoints.
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Analysis
by VulDB Data Team • 09/15/2026
The vulnerability identified in Flowise versions prior to 3.1.4 represents a critical failure in multi-tenant security architecture, specifically manifesting as an insecure direct object reference combined with broken access control mechanisms. In enterprise-grade software solutions that support multiple organizations or tenants, it is imperative that all API endpoints strictly enforce tenant isolation to ensure data segregation and operational boundaries between distinct customer entities. However, the affected implementation of organization membership and workspace management APIs fails to validate whether the authenticated user initiating a request actually belongs to the target organization's tenant scope. This architectural flaw allows an attacker who has valid authentication credentials for one account or organization to manipulate API parameters by supplying arbitrary Organization IDs associated with different tenants. By bypassing server-side checks that should verify the caller's membership within the specified organizational boundary, the application erroneously processes these requests as legitimate administrative actions.
The operational impact of this vulnerability is severe, granting attackers the ability to escalate privileges and compromise entire enterprise environments without requiring additional exploitation techniques beyond basic API interaction. Specifically, an authenticated user can exploit this flaw to add themselves as a member with owner-level permissions within any organization whose ID they can guess or enumerate. Once elevated to an organizational owner role, the attacker gains full administrative control over that entity's resources. This includes the ability to create new workspaces, manage team members, and potentially access sensitive data stored within those isolated environments. The breach of tenant isolation effectively collapses the security perimeter between different customers or departments, leading to potential unauthorized data exposure, configuration tampering, and complete loss of integrity for the affected organizations.
From a classification perspective, this vulnerability aligns with CWE-284, which describes Improper Access Control, as well as CWE-639, Injection of Critical Data into an Untrusted Context via Indirect Reference Manipulation. The attack vector is consistent with MITRE ATT&CK technique T1078, Valid Accounts, where the adversary leverages legitimate credentials to gain access, followed by T1078.004, Cloud Account, and potentially T1548.003, Abuse Elevation Control Mechanism: Bypass User Interface Restrictions if graphical interfaces are also susceptible. The core issue lies in the lack of server-side authorization checks that verify the relationship between the authenticated session's tenant context and the resource identifier provided in the request payload.
To mitigate this vulnerability, organizations must immediately upgrade to Flowise version 3.1.4 or later, where these access control flaws have been addressed by developers. In addition to patching, security teams should implement robust middleware that enforces strict multi-tenancy checks on all API endpoints handling organizational data. This involves validating the user's tenant ID against the requested resource's tenant identifier before processing any state-changing operations such as adding members or creating workspaces. Furthermore, implementing comprehensive logging and monitoring for unusual patterns in organization membership changes can help detect potential exploitation attempts early. Regular security audits focusing on access control logic and automated testing using tools that simulate cross-tenant attacks are recommended to ensure the integrity of multi-tenant isolation mechanisms remains intact across all application modules.