CVE-2026-53455: Blueprint Studio RCE Vulnerability

CVE-2026-53455 Overview

Blueprint Studio, a VS Code-like file editor for Home Assistant configuration files, contains a command injection vulnerability [CWE-78] in versions prior to 2.5.2. The flaw resides in custom_components/blueprint_studio/backend/git_manager.py, where the component generates a shell-based Git credential helper by interpolating configured Git usernames and tokens directly into executable helper script content. Because credential values are not validated, an attacker able to set Git credentials can inject newline characters or shell syntax. When Git invokes the generated credential helper, the injected commands execute with the operating-system privileges of Home Assistant.

Critical Impact
Injected shell commands run under the Home Assistant process, allowing attackers to access or modify Home Assistant configuration data and any other resources reachable by that user context.

Affected Products

Blueprint Studio versions prior to 2.5.2
Home Assistant instances with Blueprint Studio custom component installed
Environments where Git credentials can be configured through Blueprint Studio

Discovery Timeline

2026-08-18 - CVE-2026-53455 published to NVD
2026-08-19 - Last updated in NVD database

Technical Details for CVE-2026-53455

Vulnerability Analysis

The vulnerability is an OS command injection issue in the Git credential helper generation logic. Blueprint Studio builds a shell script that Git invokes to supply credentials during remote operations such as git push or git fetch. The generation routine embeds user-supplied username and token strings directly into the script body without escaping or validating the input.

Because the resulting file is executed by a shell, any newline (\n) or shell metacharacter contained in the credential fields is interpreted as script content. An attacker who can set the Git credential configuration can therefore append arbitrary commands that run when Git next requests credentials. The commands execute with the same operating-system privileges as the Home Assistant process, providing access to configuration files, secrets, and services managed by that account.

Root Cause

The root cause is unsafe string interpolation of untrusted input into an executable shell script. The git_manager.py module treats the Git username and token as literal strings rather than as data that must be quoted or written to a file the shell will not parse. There is no character allow-list, no rejection of newlines, and no use of Git's file-based credential mechanisms that avoid shell interpretation.

Attack Vector

Exploitation requires the ability to write Git credential values through Blueprint Studio. Because Blueprint Studio is registered as an admin-only panel, this typically means an authenticated administrator or an attacker who has compromised an administrative session. Once credentials are set, any subsequent Git operation that triggers the credential helper executes the injected payload under the Home Assistant service account.

python

# Patch excerpt from custom_components/blueprint_studio/backend/git_manager.py
import re
import shutil
import subprocess
import tempfile
from pathlib import Path
from typing import Any

Source: GitHub Commit 943aed0

The fix introduces tempfile handling so credentials are written to a controlled file rather than interpolated into an executable shell script.

python

# Patch excerpt from custom_components/blueprint_studio/backend/api.py
_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",
})

Source: GitHub Commit 943aed0

The companion patch tightens the admin-only action list, aligning backend privilege with the admin-only UI panel.

Detection Methods for CVE-2026-53455

Indicators of Compromise

Unexpected shell script content within Git credential helper files generated by Blueprint Studio
Newline characters or shell metacharacters (;, &&, |, `, $()) present in stored Git usernames or tokens
Child processes of the Home Assistant service spawning shells such as sh, bash, or /bin/sh -c during Git operations
Unexplained modifications to files under the Home Assistant configuration directory following a Git action

Detection Strategies

Inspect custom_components/blueprint_studio/backend/git_manager.py and any generated credential helper scripts on disk for embedded commands
Audit Home Assistant logs for Git operations correlated with process creation events that do not match expected Git binaries
Review stored Blueprint Studio Git credential configurations for values containing control characters or shell syntax

Monitoring Recommendations

Enable process-execution telemetry on the host running Home Assistant and alert on shell invocations parented by the Home Assistant process
Monitor file integrity on the Blueprint Studio installation directory to catch tampering with credential helper scripts
Log and review all administrative changes to Blueprint Studio Git settings, including username and token updates

How to Mitigate CVE-2026-53455

Immediate Actions Required

Upgrade Blueprint Studio to version 2.5.2 or later, which replaces shell interpolation with safe file-based credential handling
Rotate any Git tokens previously stored in Blueprint Studio, since they may have been exposed through injected commands
Review Home Assistant administrator accounts and remove unused or unnecessary admin access to the Blueprint Studio panel

Patch Information

The issue is fixed in Blueprint Studio 2.5.2. The patch is described in the GitHub Security Advisory GHSA-wjpc-mc3f-w5rg and released via GitHub Release v2.5.2. Code changes are available in GitHub Commit 943aed0.

Workarounds

Remove or disable the Blueprint Studio custom component until the upgrade to 2.5.2 can be applied
Restrict administrative access to the Home Assistant instance so only trusted operators can configure Git credentials
Avoid configuring Git credentials through Blueprint Studio on vulnerable versions; use Home Assistant's underlying Git tooling instead

bash

# Upgrade Blueprint Studio via HACS or manual replacement, then restart Home Assistant
cd /config/custom_components/blueprint_studio
git fetch --tags
git checkout v2.5.2
# Restart Home Assistant to load the patched component
ha core restart