Discourse is an open source platform for community discussion. Prior to version 2.8.4 on the stable branch and 2.9.0beta5 on the beta and tests-passed branches, inviting users on sites that use single sign-on could bypass the must_approve_users check and invites by staff are always approved automatically. The issue is patched in Discourse version 2.8.4 on the stable branch and version 2.9.0.beta5 on the beta and tests-passed branches. As a workaround, disable invites or increase min_trust_level_to_allow_invite to reduce the attack surface to more trusted users.
Weakness
The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action.
Affected Software
| Name |
Vendor |
Start Version |
End Version |
| Discourse |
Discourse |
* |
2.8.4 (excluding) |
| Discourse |
Discourse |
2.9.0-beta1 (including) |
2.9.0-beta1 (including) |
| Discourse |
Discourse |
2.9.0-beta2 (including) |
2.9.0-beta2 (including) |
| Discourse |
Discourse |
2.9.0-beta3 (including) |
2.9.0-beta3 (including) |
| Discourse |
Discourse |
2.9.0-beta4 (including) |
2.9.0-beta4 (including) |
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) 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.
References