Flowise Critical RCE Flaw Patched

Flowise has released a critical security update to address CVE-2026-70470, a vulnerability that allows for remote code execution. By leveraging Unicode homoglyph identifiers, an attacker can bypass existing validation filters to execute arbitrary commands on the underlying host operating system.

What's at Risk

The vulnerability affects npm/flowise and npm/flowise-components in versions prior to 3.1.3. Organizations running internet-facing instances of Flowise are at the highest risk, as the application's design allows for the execution of Python code via the Pyodide environment.

Because Flowise nodes often handle data processing tasks, an attacker who can influence input to these nodes may gain full control over the host server. This includes the ability to read sensitive files, modify system configurations, or deploy further malicious payloads, effectively compromising the entire host environment.

How the Flaw Works

This vulnerability is a classic example of an input validation bypass. Developers often use blacklists to block dangerous keywords or functions, but these defenses frequently fail when they do not account for how different programming languages or environments interpret character encoding. When a security filter relies on ASCII-based regex patterns to identify forbidden code, it can be circumvented by using alternative character representations that the underlying interpreter eventually normalizes and executes as the original, forbidden command.

In this specific case, the validator fails to recognize Unicode homoglyphs—characters that look like standard ASCII letters but have different binary representations. Because the Python interpreter performs normalization on identifiers, these disguised characters are converted back into executable code. Once the filter is bypassed, the attacker can bridge the gap between the Python sandbox and the host operating system, leading to full remote code execution.

How to Protect Your Systems

• Update Flowise and flowise-components to version 3.1.3 or later immediately to patch the validation logic.
• Restrict network access to the Flowise management interface, ensuring it is not exposed to the public internet.
• Implement the principle of least privilege by running the Flowise service under a dedicated, low-privilege system user.
• Monitor system logs for unusual process execution patterns or unexpected outbound network connections from the Flowise host.
• Audit all custom Python nodes and integrations to ensure they follow secure coding practices and do not rely solely on blacklists for security.

Given the critical severity of this flaw and its potential for complete system takeover, administrators should prioritize applying the 3.1.3 patch across all production environments. Relying on perimeter defenses alone is insufficient when the vulnerability exists within the application's core input processing logic.