OpenFGA is a high-performance and flexible authorization/permission engine built for developers and inspired by Google Zanzibar. OpenFGA v1.8.5 to v1.11.2 ( openfga-0.2.22<= Helm chart <= openfga-0.2.51, v.1.8.5 <= docker <= v.1.11.2) are vulnerable to improper policy enforcement when certain Check calls are executed. The vulnerability requires a model that has a a relation directly assignable by a type bound public access and assignable by type bound non-public access, a tuple assigned for the relation that is a type bound public access, a tuple assigned for the same object with the same relation that is not type bound public access, and a tuple assigned for a different object that has an object ID lexicographically larger with the same user and relation which is not type bound public access. This vulnerability is fixed in v1.11.3.
Weakness
The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.
Potential Mitigations
- Divide the product into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) [REF-229] to enforce the roles at the appropriate boundaries.
- Note that this approach may not protect against horizontal authorization, i.e., it will not protect a user from attacking others with the same role.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
- For example, consider using authorization frameworks such as the JAAS Authorization Framework [REF-233] and the OWASP ESAPI Access Control feature [REF-45].
- For web applications, make sure that the access control mechanism is enforced correctly at the server side on every page. Users should not be able to access any unauthorized functionality or information by simply requesting direct access to that page.
- One way to do this is to ensure that all pages containing sensitive information are not cached, and that all such pages restrict access to requests that are accompanied by an active and authenticated session token associated with a user who has the required permissions to access that page.