Broken Access Control in Rocket with Mongodb

Broken Access Control is a common API security risk (OWASP API Top 10 #1) and in the Rocket + MongoDB stack it typically arises when authorization checks are missing or inconsistent before data is read or written. Rocket routes often deserialize incoming JSON into strongly-typed request structs, but if a handler uses the authenticated user’s identity to build a MongoDB query without enforcing object-level permissions, it can inadvertently expose or modify records that belong to other subjects.

For example, an endpoint like /users/:user_id/records may authenticate a JWT to identify a user ID, then pass that ID into a MongoDB find filter. If the handler trusts the client-supplied user_id parameter rather than deriving the subject from the authenticated session, an attacker can change the parameter to access another user’s records. This is a Broken Object Level Authorization (BOLA) / IDOR pattern, where the API surface exposes MongoDB document identifiers or query filters without validating that the requesting actor owns those documents.

In Rocket, this can also occur when struct-based filters are constructed from request query parameters or body fields and passed directly to a MongoDB collection. Consider a search endpoint that builds a MongoDB BSON document from user input without scoping to the requesting user. Without a server-side subject binding, the query can return documents across users. The risk is amplified when the MongoDB _id or other opaque references are exposed in URLs or error messages, because these become easy targets for IDOR enumeration. Even when authentication is enforced, missing or weak authorization logic in Rocket request guards or managed state can allow an authenticated user to traverse relationships (e.g., org_id, team_id) that should restrict visibility.

Another scenario involves privilege escalation via BFLA (Business Logic Flow Attacks) where API sequences bypass intended step-by-step checks. If Rocket handlers assume prior middleware has enforced ownership but later handlers omit those checks, MongoDB operations may execute with over-permissive scopes. For instance, an update route might include the user identifier in the update specification rather than hard-scoping the update filter to the authenticated subject’s tenant or team. This leads to updates that should be forbidden. Because Rocket does not automatically enforce object ownership, developers must explicitly bind the authenticated subject into every MongoDB query and command, and validate that the resulting filter is aligned with the intended access policy.

OpenAPI/Swagger analysis helps surface these issues by correlating runtime calls with the spec. When a path parameter such as {user_id} is used in a MongoDB query without a clear security requirement that ties it to the authenticated subject, the scan can flag the operation as a potential BOLA/IDOR. The scanner tests unauthenticated and authenticated probes to observe whether the endpoint enforces subject scoping, and maps findings to frameworks like OWASP API Top 10 and SOC2 controls to provide prioritized remediation guidance.

To fix Broken Access Control in Rocket with MongoDB, bind the authenticated subject into every query and update, and avoid relying on client-supplied identifiers for scoping. Below are concrete, idiomatic Rust examples using the official MongoDB driver and Rocket request guards.

1) Always derive subject from authentication, not request input

Instead of reading a user_id from the URL or JSON body to build a filter, extract the subject from your auth guard and use it as the primary filter key. For example, if you store a user identifier in the JWT claims:

use rocket::State;
use rocket::serde::json::Json;
use rocket::Request;
use mongodb::{bson::doc, Collection};

struct Claims {
    sub: String,
}

#[rocket::get("/records")]
async fn list_records(
    claims: &Claims,
    coll: &State>,
) -> Json> {
    let filter = doc! { "user_id": &claims.sub };
    let cursor = coll.find(filter, None).await.unwrap_or_default();
    let docs: Vec<_> = cursor.try_collect().unwrap_or_default();
    Json(docs)
}

This ensures the user can only query records where the user_id field matches their own subject, regardless of any client-supplied parameters.

2) Use a request guard to enforce ownership on updates

For mutation endpoints, validate that the target document belongs to the authenticated subject before performing an update. Combine a document-level fetch with an ownership check, or embed the subject in the filter:

use rocket::serde::json::Json;
use rocket::http::Status;
use mongodb::{bson::{doc, oid::ObjectId}, options::FindOneAndUpdateOptions};

#[rocket::put("/records/<id>")]
async fn update_record(
    id: <mongodb::bson::oid::ObjectId>,
    claims: &Claims,
    coll: &State>,
    body: Json<serde_json::Value>,
) -> Result<Json<serde_json::Value>, Status> {
    let filter = doc! {
        "_id": id,
        "user_id": &claims.sub,
    };
    let update = doc! { "$set": body.0 };
    let opts = FindOneAndUpdateOptions::builder().return_document(mongodb::options::ReturnDocument::After).build();
    let maybe_updated = coll.find_one_and_update(filter, update, opts).await.map_err(|_| Status::InternalServerError)?;
    match maybe_updated {
        Some(doc) => Ok(Json(doc)),
        None => Err(Status::Unauthorized), // Either wrong ID or subject mismatch
    }
}

This pattern prevents privilege escalation by ensuring the update applies only when both the record ID and the subject match.

3) Scopify query parameters and avoid raw exposure of MongoDB identifiers

If you must accept query parameters for filtering, validate and scope them against the authenticated subject. Do not directly inject parameters into the MongoDB filter without checks:

use rocket::request::Query;
use serde::Deserialize;

#[derive(Deserialize)]
struct RecordQuery {
    #[serde(rename = "type")]
    record_type: Option,
}

#[rocket::get("/records")]
async fn filtered_records(
    claims: &Claims,
    query: Query<RecordQuery>,
    coll: &State>,
) -> Json<Vec<serde_json::Value>> {
    let mut filter = doc! { "user_id": &claims.sub };
    if let Some(t) = &query.record_type {
        filter.insert("type", t);
    }
    let cursor = coll.find(filter, None).await.unwrap_or_default();
    Json(cursor.try_collect().unwrap_or_default())
}

By embedding user_id first and then augmenting with validated inputs, you keep the authorization boundary tight. For sensitive operations, consider additional checks such as team or role membership stored in the user’s claims.

4) Security and observability

Ensure your MongoDB connection uses TLS and that your connection strings do not leak through logs or error messages. In Rocket, configure fairings to scrub sensitive data from request and response logs. Combine these coding practices with continuous scanning; the middleBrick CLI (middlebrick scan <url>) can be integrated into development workflows to detect missing subject scoping and other Broken Access Control patterns before deployment. For CI/CD enforcement, the middleBrick GitHub Action can fail builds when risk scores drop below your chosen threshold, and the MCP Server allows AI coding assistants to surface authorization issues during implementation.