Auth Bypass in Axum with Cockroachdb

An Auth Bypass in an Axum service that uses CockroachDB typically occurs when authentication state or permissions are enforced at the application layer but not consistently validated against each request or when session/identity assumptions are made without verifying credentials on each database interaction. Axum is a web framework that relies on explicit middleware for authentication; if routes that interact with CockroachDB are not protected by an authentication guard, an unauthenticated user may reach handlers that execute SQL queries.

In a typical Axum + CockroachDB setup, developers may pass a database connection pool (e.g., via State) to handlers and construct SQL such as SELECT * FROM users WHERE id = $1 using parameters from path segments or headers. If the handler does not validate that the requester is the owner of the requested resource (e.g., missing ownership checks or using an ID supplied by the client without verifying it matches the authenticated user), this can lead to IDOR-like access, effectively an auth bypass where one user can view or modify another’s data by changing numeric IDs.

Another vector specific to CockroachDB arises from its PostgreSQL compatibility and its use of crdb_internal or secondary indexes: an attacker may supply crafted query parameters that cause the query planner to behave differently or bypass intended filters when authorization logic is implemented as post-query checks rather than predicate-level constraints. For example, if an Axum handler builds dynamic SQL without parameterizing inputs and includes the user identifier as a string concatenation, an attacker could potentially inject SQL fragments that alter the WHERE clause, though this is more SQL injection than pure auth bypass; however, improper use of optional parameters can unintentionally expose other users’ records.

Consider an Axum handler that retrieves a user profile by ID from CockroachDB without confirming that the authenticated user owns that ID. If the route relies on a path parameter like /profile/:user_id and directly queries CockroachDB with that ID using a parameterized query, the absence of an ownership check means any authenticated or unauthenticated user (depending on middleware configuration) can enumerate or access other users’ profiles simply by changing the ID. This is an auth bypass because the application fails to enforce that the requesting identity matches the requested resource identity.

Middleware gaps compound the risk. Axum does not enforce authentication by default; developers must add extractors or guards. If the authentication extractor sets user identity in request extensions but downstream handlers skip extracting that identity for authorization, the handler may execute CockroachDB queries in a context where the user’s actual permissions are unknown. Additionally, CockroachDB’s serializable isolation can mask race conditions: two requests may concurrently read and write shared data if application-level locking is absent, allowing an attacker to exploit timing to access or modify data they should not.

To detect such issues, middleBrick scans unauthenticated attack surfaces and checks whether endpoints that interact with CockroachDB enforce authentication and proper ownership. It also examines OpenAPI specs to see whether paths that reach database-influencing operations are guarded, highlighting missing security schemes or inconsistent use of security requirements that could enable an auth bypass in an Axum service backed by CockroachDB.

Remediation centers on ensuring every Axum handler that interacts with CockroachDB validates the requester’s identity and enforces ownership or role-based access before constructing and executing SQL. Use typed extractors to obtain the authenticated subject and bind it to the database query so that the application never trusts path or query parameters alone for access control.

First, define a reusable extractor that retrieves the user identity from your authentication scheme (e.g., JWT) and attach it to routes that require protection. Then, in the handler, use the extracted identity to parameterize queries with placeholders, ensuring that the WHERE clause includes both the target identifier and the authenticated user ID.

// Axum handler with proper ownership check against CockroachDB
use axum::{routing::get, Router, extract::State, http::StatusCode};
use serde::Serialize;
use sqlx::postgres::PgPoolOptions;
use std::net::SocketAddr;

struct AppState {
    pool: sqlx::PgPool,
}

#[derive(Serialize)]
struct ProfileResponse {
    user_id: i64,
    email: String,
}

async fn get_profile(
    State(state): State<AppState>,
    // Authenticated subject from extractor
    user_id: i64,
    // Path parameter — must be validated against user_id
    target_id: i64,
) -> Result<impl axum::response::IntoResponse, (StatusCode, String)> {
    // Enforce ownership: only allow access when IDs match
    if user_id != target_id {
        return Err((StatusCode::FORBIDDEN, "Access denied".to_string()));
    }

    let profile = sqlx::query_as!(
        ProfileResponse,
        "SELECT id, email FROM users WHERE id = $1 AND id = $2",
        user_id,
        target_id
    )
    .fetch_optional(&state.pool)
    .await
    .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, e.to_string()))?;

    match profile {
        Some(p) => Ok(axum::Json(p)),
        None => Err((StatusCode::NOT_FOUND, "Profile not found".to_string())),
    }
}

#[tokio::main]
async fn main() {
    let pool = PgPoolOptions::new()
        .connect("postgresql://user:pass@host:26257/dbname?sslmode=require")
        .await
        .expect("Failed to connect");

    let app = Router::new()
        .route("/profile/:user_id", get(get_profile))
        .with_state(AppState { pool });

    let addr = SocketAddr::from(([127, 0, 0, 1], 3000));
    axum::Server::bind(&addr)
        .serve(app.into_make_service())
        .await
        .unwrap();
}

Second, for broader protection, implement a guard that ensures all routes interacting with CockroachDB require authentication. In Axum, you can layer extractors so that handlers only execute when a valid identity is present. Combine this with SQL that always includes the authenticated user ID as a filter condition, even when the path ID appears to match, to prevent logic mistakes.

Third, avoid dynamic SQL concatenation with user-controlled identifiers when possible; prefer static parameterized queries. If you must build dynamic predicates, use sqlx’s query builder or an ORM that enforces type safety. This reduces the chance of accidentally omitting the user filter or misplacing conditions, which is a common root cause of auth bypass in Axum services using CockroachDB.

Finally, validate and normalize inputs before using them in queries. For example, ensure numeric IDs are strictly integers and not coercible strings, and apply consistent row-level security patterns in your CockroachDB schema (e.g., using session variables or application-enforced tenant IDs) so that even if an application layer check is missed, the database can still enforce boundaries.