critical CVSS 9.8

CVE-2026-41264·Python vulnerability

Flowise is a drag & drop user interface to build a customized large language model flow. Prior to 3.1.0, the specific flaw exists within the run method of the CSV_Agents class. The issue results from the lack of proper sandboxing when evaluating an LLM generated python script. An attacker can leverage this vulnerability to execute code in the context of the user running the server. Using prompt injection techniques, an unauthenticated attacker with the ability to send prompts to a chatflow using the CSV Agent node may convince an LLM to respond with a malicious python script that executes attacker controlled commands on the Flowise server. This vulnerability is fixed in 3.1.0.

Severity
critical
Software
Python
Fixed in
3.1.0
Published
2026-04-23

Affected versions

Until: 3.1.0

Fixed in: 3.1.0

How to fix this CVE

Upgrade Flowise to version 3.1.0 or later to patch the CSV_Agents class vulnerability that allows unauthenticated remote code execution through prompt injection. The flaw permits attackers to inject malicious Python code that executes on the server due to insufficient sandboxing of LLM-generated scripts. Immediately update your deployment and review any chat logs for suspicious LLM outputs containing Python code.

sudo dnf update python3

Defensia detects this vulnerability

What an exploitation attempt looks like

Sample log line indicative of exploitation attempts:

POST request to /api/prediction with JSON payload containing CSV_Agents node execution; response contains Python code patterns like 'import', 'exec', 'subprocess', or 'os.system' in LLM-generated text; followed by unexpected child process creation with elevated privilege commands

WAF mitigation (if patching is not yet possible)

Add this rule to your WAF to block exploitation attempts while you schedule the patch. 

Block POST requests to /api/prediction endpoints containing keywords commonly used in prompt injection attacks ('exec', 'import os', '__import__', 'subprocess.call', 'eval', 'compile') in the request body; implement strict LLM output validation to reject responses containing Python code syntax before execution

How to check if you are affected

  1. Step 1: Check Flowise version with 'npm list flowise' or review your package.json to confirm current version is below 3.1.0
  2. Step 2: Identify all active chatflows using the CSV_Agents node by inspecting the Flowise configuration files in ~/.flowise or your installation directory
  3. Step 3: Search application logs for suspicious patterns like 'import os', 'subprocess', 'exec(', or 'eval(' appearing in LLM response outputs, especially those preceded by prompt input containing injection keywords
  4. Step 4: Verify upgrade by running 'npm list flowise' and confirming version 3.1.0 or higher is installed, then restart the Flowise service

Indicators of compromise

  • Flowise versions < 3.1.0 with CSV_Agents node configuration
  • HTTP requests to /api/prediction containing prompt injection payloads with Python keywords
  • Unexpected child process spawning from Flowise service with shell commands

FAQ

What is CVE-2026-41264?

This vulnerability in Flowise allows attackers to execute arbitrary code on the server by injecting malicious prompts into chatflows using the CSV_Agents node, bypassing authentication entirely due to missing code sandboxing.

Is CVE-2026-41264 being actively exploited?

No active exploitation has been reported according to CISA's Known Exploited Vulnerabilities catalog, and no public exploits are currently available.

What versions of Flowise are affected by CVE-2026-41264?

All versions of Flowise prior to 3.1.0 are affected by this vulnerability, particularly those with CSV_Agents functionality enabled.

How do I check if my server is vulnerable to CVE-2026-41264?

Run 'npm list flowise' to verify your installed version; if it is below 3.1.0 and you have CSV_Agents nodes active, your deployment is vulnerable.

Does Defensia detect CVE-2026-41264?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Flowise is installed on a monitored server, CVE-2026-41264 will appear in your dashboard with remediation steps.

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References

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