Technical Analysis & Defensive Guide: CVE-2025-3248 (Langflow Code Injection)

An educational reference and defensive analysis of CVE-2025-3248, a critical code injection vulnerability affecting Langflow.

📌 Vulnerability Profile

• CVE ID: CVE-2025-3248
• Vulnerability Type: Remote Code Execution (RCE) / Code Injection (CWE-94)
• Affected Software: Langflow (Versions < 1.3.0)
• Impact Severity: Critical (Unauthenticated Remote Code Execution)
• Target Endpoint: /api/v1/validate/code

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🔍 Technical Mechanism

Langflow is an open-source visual framework for building multi-agent and RAG applications. To allow developers to write custom Python components, it provides logic to validate and execute code snippets on the fly.

The Root Cause

1. Lack of Input Sanitization: In versions prior to 1.3.0, the /api/v1/validate/code endpoint accepts Python code strings from user requests.
2. Insecure Execution: The backend processes this code directly using dynamic evaluation mechanisms (such as exec() or similar runtime evaluators) without sufficient sandboxing, input sanitization, or execution restriction.
3. No Authentication Required: The endpoint is exposed by default to unauthenticated users, allowing anyone with network access to trigger execution.

Consequently, an attacker can supply Python system-execution payloads (such as utilizing the os or subprocess modules) to execute arbitrary commands under the system privileges of the Langflow service runner.

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🛠️ Mitigation & Hardening

If you are running or administering Langflow instances, apply the following controls:

1. Upgrade Immediately

The vulnerability is resolved in Langflow version 1.3.0 and later. Ensure your deployment pipelines are updated:

pip install --upgrade langflow

2. Network Segmentation & Access Control

• Restrict API Exposure: Never expose Langflow's admin interface or API endpoints directly to the public internet. Use a Reverse Proxy (e.g., Nginx, Traefik) or a Cloud API Gateway to restrict access.
• Enable Authentication: Ensure robust user authentication is enforced on all API routes before they reach the backend service.

3. Container Isolation (Principle of Least Privilege)

If running Langflow within Docker or Kubernetes:

• Do not run the container process as root.
• Use container security profiles (AppArmor, Seccomp) to restrict system calls.
• Use a read-only root filesystem where possible and restrict network egress from the container to only trusted destinations.

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⚠️ Disclaimer

This documentation is maintained solely for authorized security assessment, defense hardening, and educational purposes. Ensure all testing is restricted to self-hosted, authorized laboratory environments.

Finding Targets

To find potential targets, use Fofa and Shodan.io

Run Poc

First, clone the repository:

git clone https://github.com/zoly-zoly/CVE-2025-3248.git

Run the Exploit:

python3 CVE-2025-3248.py --target http://IP:Port --cmd "Command"