[CRITICAL] Multi-Tenant Isolation Bypass in College Platform Backend
A critical security vulnerability has been identified in a multi-tenant college platform where isolation between different colleges is not consistently enforced across backend controllers. A malicious user could potentially access data from other colleges by manipulating the `college_id` parameter in requests.
**Severity:** CRITICAL
**Affected Components:** Backend Controllers (multiple), Authentication Middleware, Authorization Layer.
**Evidence:** The authentication middleware sets `req.user.college_id` from the decoded JWT token, but this value is not subsequently verified against the database, creating a trust boundary vulnerability.
**How to Reproduce:**
1. Login as a teacher from College A.
2. Capture the JWT token from cookies.
3. Decode the token and modify the `college_id` to College B's ID.
4. Re-encode the token and replace it.
5. Make API requests to endpoints like `/api/students` or `/api/teachers`.
6. **Expected Result:** Access denied due to wrong college.
7. **Actual Result:** The system may return data belonging to College B.
**Security Impact:**
- Data breach between separate college tenants.
- Fundamental violation of multi-tenant data isolation.
- Potential for significant GDPR and other regulatory compliance violations.
**Recommended Fix:**
1. Implement server-side verification of the user's `college_id` against the database after JWT token verification, not relying solely on the token payload.
2. Add a dedicated college isolation middleware to all relevant routes to enforce tenant boundaries.
3. Implement row-level security (RLS) or similar query-level filters in all database queries to ensure data segregation.
**Verification Requested:** Security team verification of the bypass, comprehensive testing of all endpoints for college-level access control flaws, and confirmation of fix implementation before any production deployment.
**References:** `backend/src/middlewares/auth.middleware.js`, `backend/src/controllers/student.controller.js`.