CVE-2026-27483: MindsDB Path Traversal RCE Vulnerability

CVE-2026-27483 Overview

CVE-2026-27483 is a path traversal vulnerability in MindsDB, a platform for building artificial intelligence from enterprise data. Prior to version 25.9.1.1, the /api/files interface contains a critical path traversal flaw that an authenticated attacker can exploit to achieve remote command execution. The vulnerability exists in the "Upload File" module, which corresponds to the API endpoint /api/files. Since the multipart file upload does not perform security checks on the uploaded file path, an attacker can perform path traversal by using ../ sequences in the filename field. The file write operation occurs before calling clear_filename and save_file, meaning there is no filtering of filenames or file types, allowing arbitrary content to be written to any path on the server.

Critical Impact

Authenticated attackers can exploit this path traversal vulnerability to write arbitrary files to any location on the server, potentially leading to remote command execution and complete system compromise.

Affected Products

• MindsDB versions prior to 25.9.1.1

Discovery Timeline

• 2026-02-24 - CVE CVE-2026-27483 published to NVD
• 2026-02-26 - Last updated in NVD database

Technical Details for CVE-2026-27483

Vulnerability Analysis

This path traversal vulnerability (CWE-22) in MindsDB allows authenticated attackers to escape the intended upload directory and write files to arbitrary locations on the server filesystem. The flaw resides in the file upload handling logic of the /api/files endpoint, where the application fails to sanitize user-supplied filenames before performing write operations. An authenticated user can craft a malicious filename containing path traversal sequences (../) to navigate outside the designated upload directory.

The vulnerability is particularly dangerous because the file write operation occurs before any sanitization functions like clear_filename and save_file are called. This means an attacker can write files with any content type and any filename to any writable path on the server. By strategically placing malicious files (such as Python scripts, cron jobs, or SSH keys), an attacker can achieve remote command execution on the underlying system.

Root Cause

The root cause of this vulnerability is improper input validation in the multipart file upload handler. The application processes the filename field from the multipart form data without first validating or sanitizing it for path traversal sequences. The file write operation is performed before the clear_filename function is invoked, creating a race condition where malicious filenames are processed before security checks can be applied. This represents a classic case of insufficient input validation combined with insecure file handling practices.

Attack Vector

An authenticated attacker can exploit this vulnerability by sending a crafted multipart file upload request to the /api/files endpoint. The attacker includes path traversal sequences in the filename field to navigate to a target directory outside the intended upload location. Successful exploitation allows writing arbitrary content to any writable path on the server, which can be leveraged for remote command execution through various techniques such as:

• Writing malicious Python scripts to application directories
• Overwriting configuration files
• Placing SSH authorized keys for persistent access
• Creating cron jobs for scheduled command execution

The security patch addresses this by importing Path from pathlib for proper path handling and upgrading the python-multipart dependency:

 import tarfile
 import tempfile
 import zipfile
+from pathlib import Path
 from urllib.parse import urlparse
 
 import multipart

Source: GitHub Commit

The dependency update in requirements.txt:

 werkzeug == 3.0.6
 flask-restx >= 1.3.0, < 2.0.0
 pandas == 2.2.3
-python-multipart == 0.0.18
+python-multipart == 0.0.20
 cryptography>=35.0
 psycopg[binary]
 psutil~=7.0

Source: GitHub Commit

Detection Methods for CVE-2026-27483

Indicators of Compromise

• HTTP POST requests to /api/files containing ../ or encoded path traversal sequences (%2e%2e%2f) in filename parameters
• Unexpected file creation in system directories outside the MindsDB upload folder
• Modified system configuration files, cron jobs, or SSH authorized_keys files with recent timestamps
• Unusual file write activity by the MindsDB process to paths outside its working directory

Detection Strategies

• Monitor web application logs for multipart upload requests to /api/files with suspicious filename patterns containing path traversal sequences
• Implement file integrity monitoring on critical system directories to detect unauthorized file writes
• Deploy network-level detection rules to identify HTTP requests with path traversal payloads targeting MindsDB endpoints
• Review MindsDB application logs for failed or successful file upload operations with unusual destination paths

Monitoring Recommendations

• Enable verbose logging for the MindsDB application to capture all file upload operations with full filename details
• Configure SIEM alerts for path traversal patterns in web server and application logs
• Implement endpoint detection to monitor for unexpected child processes spawned by the MindsDB service
• Establish baseline file system activity for MindsDB and alert on deviations indicating potential exploitation

How to Mitigate CVE-2026-27483

Immediate Actions Required

• Upgrade MindsDB to version 25.9.1.1 or later immediately
• Review server file systems for any unauthorized files created through path traversal exploitation
• Audit MindsDB authentication logs to identify potentially compromised accounts
• Restrict network access to MindsDB instances to trusted IP ranges while patching is completed

Patch Information

MindsDB has released version 25.9.1.1 which patches this vulnerability. The fix implements proper path handling using Python's pathlib.Path module and upgrades the python-multipart dependency from version 0.0.18 to 0.0.20. For detailed information about the patch, refer to the GitHub Security Advisory GHSA-4894-xqv6-vrfq and the GitHub Release v25.9.1.1.

Workarounds

• Deploy a web application firewall (WAF) rule to block requests containing path traversal sequences in multipart form fields
• Implement network segmentation to limit access to MindsDB instances from untrusted networks
• If possible, disable or restrict access to the /api/files endpoint until the patch can be applied
• Run MindsDB under a restricted user account with minimal filesystem write permissions to limit exploitation impact

# Example: Restrict MindsDB service permissions (Linux)
# Create dedicated user with limited permissions
useradd -r -s /bin/false mindsdb-service

# Set ownership of MindsDB directory
chown -R mindsdb-service:mindsdb-service /opt/mindsdb

# Restrict write permissions to upload directory only
chmod 700 /opt/mindsdb/uploads