CISA Alerts to Active Exploitation of Langflow CVE-2025-3248

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has mandated federal agencies to patch a critical vulnerability (CVE-2025-3248) in Langflow by May 26, 2025, following evidence of active exploitation.

This flaw allows unauthenticated attackers to execute arbitrary code on AI workflow servers using crafted HTTP requests.

Technical Breakdown

The vulnerability resides in Langflow’s /api/v1/validate/code endpoint, which improperly invokes Python’s exec() A function to validate user-submitted code without authentication or sandboxing.

Attackers can exploit this by embedding malicious payloads in function decorators or default arguments, which execute during code validation:

python# Example payload exploiting decorators  
@exec("import os; os.system('id > /tmp/pwned')")  
def foo():  
    pass  

# Example using default arguments  
def bar(cmd=exec("__import__('subprocess').check_output('env')")):  
    pass  

When submitted via POST request, these payloads trigger immediate code execution, enabling actions like file writes, reverse shells, or credential theft.

Risk Factor Analysis

Exploitation and Exposure

• Active Exploits: Public proof-of-concept exploits emerged on April 9, 2025, with attackers targeting AI development servers.
• Exposed Instances: 466 internet-facing Langflow servers identified globally, primarily in the U.S., Germany, and India.
• Attack Methods: Malicious HTTP POST requests bypassing authentication, often masquerading as routine API calls.

Mitigation Strategies

1. Immediate Patching: Upgrade to Langflow 1.3.0, which enforces authentication for the vulnerable endpoint.
2. Network Controls:
   • Restrict access to Langflow instances via firewalls or Zero Trust frameworks.
   • Monitor traffic to /api/v1/validate/code for anomalous patterns.
3. Defense-in-Depth:
   • Deploy web application firewalls (WAFs) to block exploit patterns.
   • Isolate Langflow servers in segmented network zones.

CISA’s advisory underscores the risks of unsecured code-validation features in AI tools, urging organizations to prioritize updates and adopt least-privilege architectures.

With Langflow’s growing adoption in AI workflows, this vulnerability highlights the critical need for secure development practices in emerging technologies.

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