An unauthenticated attacker can exploit the unprotected registration endpoint (/register) to create a new user and bypass authentication.
Critical vulnerability in Flowise 3.0.1 on-premise deployment allows unauthenticated attackers to exploit the /api/v1/account/register endpoint to add a new user and log in using it, enabling authentication bypass.
Meaning that the register functionality is by default open, allowing attackers to create an account and use the api without any restrictions or credentials.
A Flowise 3.0.1 instance was deployed via Docker for the purpose of this demonstration.
After successful deployment the instance setup organization page allows us to register the first account in the system.
Creating the first user [email protected]
Login to the account
The background request that created the first user to /api/v1/account/register
Response
We have found that it is possible to reuse the registration request multiple times without any restrictions to create an account and authenticate to the system using it.
Crafting a new request
{
"user": {
"name": "Malicious",
"email": "[email protected]",
"type": "pro",
"credential": "Password123!"
}
}
Response with 201 code “Created”
Login using newly created user (attacker)
Success login
An unauthorized user can exploit this vulnerability to register an account and gain access to the Flowise API with authenticated privileges, effectively bypassing authentication.
This is an authentication bypass vulnerability caused by an unprotected registration endpoint (/register).
Users of Flowise 3.0.1(latest) on-premise deployments are impacted. An unauthorized attacker can exploit this vulnerability to register an account after the organization set has been completed, and gain access to the Flowise API with authenticated privileges, effectively bypassing authentication.
| Software | From | Fixed in |
|---|---|---|
flowise
|
3.0.1 | 3.0.1.x |
A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.
CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.
A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.
Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.
Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.
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