CVE-2026-53453: Blueprint Studio Auth Bypass Vulnerability

CVE-2026-53453 Overview

Blueprint Studio is a VS Code-like file editor integrated into Home Assistant for editing configuration files. Versions prior to 2.5.2 expose administrator-only backend actions to any authenticated Home Assistant user. The backend fails to enforce the panel's admin-only authorization boundary consistently across API, WebSocket, upload, stream, and terminal surfaces. A non-admin user can invoke arbitrary Home Assistant services, render templates that expose state, replace strings globally, modify configuration files, upload files, and reach terminal helpers. The weakness is tracked as Missing Authorization [CWE-862] and is fixed in version 2.5.2.

Critical Impact
Any authenticated Home Assistant user, regardless of role, can invoke admin-only Blueprint Studio actions to read, modify, or execute against the underlying Home Assistant installation.

Affected Products

Blueprint Studio custom component for Home Assistant
All Blueprint Studio releases prior to 2.5.2
Home Assistant installations with the Blueprint Studio panel enabled

Discovery Timeline

2026-08-18 - CVE-2026-53453 published to NVD
2026-08-19 - Last updated in NVD database

Technical Details for CVE-2026-53453

Vulnerability Analysis

Blueprint Studio registers itself in Home Assistant as an admin-only panel. The frontend enforces admin gating, but the backend does not. Requests routed to the backend API, upload API, stream routes, terminal WebSocket, and Blueprint Studio WebSocket subscriptions accept any authenticated Home Assistant session.

This authorization gap exposes several sensitive actions to non-admin users: call_service invokes arbitrary Home Assistant services, render_template leaks state and secrets through Jinja evaluation, and global_replace modifies configuration content across files. File and stream access paths permit reading and downloading configuration data, while upload handling and terminal helpers extend the surface to shell-adjacent operations.

Root Cause

The backend previously relied on a denylist of admin-only actions that omitted several high-impact endpoints. Authorization checks were inconsistent across the API, WebSocket subscriptions, stream routes, and terminal helpers. Because the panel was marked admin-only at the UI layer, backend enforcement was assumed but not applied.

Attack Vector

An attacker needs a valid, non-admin Home Assistant account. They send crafted requests directly to Blueprint Studio backend endpoints or WebSocket subscriptions, bypassing the frontend. From there, they invoke call_service, render_template, global_replace, file streams, uploads, or terminal helpers to compromise confidentiality, integrity, and availability.

python

# Patch excerpt: custom_components/blueprint_studio/backend/api.py
# Source: https://github.com/ha-china/blueprint-studio/commit/943aed0be67f3a910b0f70a3864288d5e17e55ce

_LOGGER = logging.getLogger(__name__)

# Blueprint Studio is registered as an admin-only panel and exposes config files,
# git operations, SFTP, terminal helpers, and HA service calls. Keep the backend
# at the same privilege level as the UI instead of trying to maintain a denylist.
_ADMIN_ONLY_ACTIONS = frozenset({
    "call_service",
    "delete",
    "delete_multi",
    "global_replace",
    "git_force_push",
    "git_hard_reset",
    "git_delete_repo",
    "git_delete_remote_branch",
    "render_template",
    "restart_home_assistant",
})

The fix expands the admin-only action set to include call_service, global_replace, and render_template, and aligns backend enforcement with the admin-only panel registration.

Detection Methods for CVE-2026-53453

Indicators of Compromise

Home Assistant service calls originating from non-admin user sessions through Blueprint Studio endpoints
Unexpected render_template requests returning secrets, tokens, or state attributes
Configuration file modifications, uploads, or global string replacements outside change-management windows
Terminal WebSocket connections established by accounts without administrator role

Detection Strategies

Correlate Home Assistant audit logs with user role attributes to flag admin-only Blueprint Studio actions performed by non-admin accounts.
Inspect Blueprint Studio WebSocket traffic for subscriptions to terminal, stream, and file endpoints from unprivileged users.
Compare installed Blueprint Studio version against 2.5.2 across all Home Assistant hosts.

Monitoring Recommendations

Alert on any invocation of call_service, render_template, or global_replace through the Blueprint Studio backend.
Log and review all file upload and download activity through Blueprint Studio stream routes.
Monitor creation of new Home Assistant users and validate their assigned role before granting access to hosts running Blueprint Studio.

How to Mitigate CVE-2026-53453

Immediate Actions Required

Upgrade Blueprint Studio to version 2.5.2 or later on all Home Assistant instances.
Audit Home Assistant user accounts and remove any non-admin users that no longer require access.
Review recent configuration changes, uploaded files, and Git operations for unauthorized modifications.

Patch Information

The fix is available in Blueprint Studio v2.5.2. The remediation commit is published at GitHub Commit 943aed0. Full details are documented in GHSA-ppwq-ch6x-936g.

Workarounds

If upgrade is not immediately possible, disable the Blueprint Studio integration in Home Assistant.
Restrict Home Assistant access to trusted administrator accounts until the patch is applied.
Place Home Assistant behind network segmentation that limits reachability to authenticated administrators only.

bash

# Upgrade Blueprint Studio via HACS or manual install to v2.5.2
cd /config/custom_components/blueprint_studio
git fetch --tags
git checkout v2.5.2
# Restart Home Assistant to apply the update
ha core restart