GHSA-m837-xvxr-vqwg: Hardcoded CORS Wildcard Enables Cross-Origin Credential Abuse in Flowise

Vulnerability ID: GHSA-M837-XVXR-VQWG
CVSS Score: 6.9
Published: 2026-05-20

Flowise versions prior to 3.1.2 contain a hardcoded CORS wildcard on the Text-to-Speech (TTS) endpoint. This configuration bypasses the application's global security policies and enables cross-origin credential abuse, leading to unauthorized resource consumption and potential financial impact via third-party API quota exhaustion.

TL;DR

A hardcoded Access-Control-Allow-Origin: * header in Flowise's TTS endpoint allows malicious websites to perform unauthorized cross-origin requests. Combined with credential abuse flaws, this allows attackers to consume configured external TTS API quotas.

⚠️ Exploit Status: POC

Technical Details

Vulnerability ID: GHSA-m837-xvxr-vqwg
CVSS Score: 6.9 (v4.0)
Attack Vector: Network
CWE ID: CWE-942
Impact: Cross-Origin Credential Abuse & Quota Exhaustion
Affected Component: TTS Generation Endpoint

Affected Systems

Flowise (npm package)
Flowise Docker Image
flowise: < 3.1.2 (Fixed in: 3.1.2)

Mitigation Strategies

Upgrade the Flowise npm package to version 3.1.2 or higher.
Deploy the latest Docker image tagged 3.1.2.
Implement reverse proxy rules to strip wildcard CORS headers from the TTS endpoint.

Remediation Steps:

Identify all running instances of Flowise within the environment.
Stop the currently running Flowise service.
Update the package via npm (npm install flowise@latest) or pull the latest Docker image (docker pull flowiseai/flowise:3.1.2).
Restart the Flowise service.
Verify the remediation by inspecting the HTTP headers of the /api/v1/text-to-speech endpoint and confirming the absence of Access-Control-Allow-Origin: *.