External risk intelligence

FastapiAdmin Authentication Bypass via Auto-Login

CVE advisorySeverity: CRITICAL (CVSS 9.3)

CVE-2026-111641

FastapiAdmin is an administrative interface for web applications. Such tools are commonly deployed as web applications or API management endpoints that are often exposed to the internet or reachable via internal network interfaces to facilitate remote management, making the vulnerable authentication and API surface likely to be exposed in many deployment scenarios.

Missing Authentication

Halo Surface Signal: 4 out of 5 — likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A vulnerability has been identified in FastapiAdmin through version 3.0, allowing unauthenticated access to user sessions through unprotected auto-login endpoints. This issue enables attackers to potentially gain full administrative control over affected systems by exploiting these endpoints to obtain user sessions, including those of superusers.

Unprotected auto-login lets anyone steal user sessions.
Admin systems can be compromised without any credentials.
Confirm if this administrative tool is in use.

Attack Path

How an attacker could exploit the issue

An attacker could exploit this vulnerability by accessing unprotected auto-login endpoints on a FastapiAdmin deployment. By leveraging these endpoints, an unauthenticated attacker can bypass normal authentication mechanisms, obtain session tokens for any user, and ultimately gain full administrative control over the application.

No authentication is required to start.
Unprotected auto-login endpoints are abused.
Full administrative control is the risk.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could allow an unauthenticated attacker to bypass authentication and gain administrative control over affected systems. By exploiting unprotected auto-login endpoints, an attacker could list users, create a superuser token, and then impersonate any user to gain full administrative privileges.

Administrative sessions and user data.
Abuse of unprotected auto-login endpoints.
Unauthorized administrative access.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability in FastapiAdmin's auto-login endpoints requires immediate attention from the application owner and platform team responsible for managing administrative interfaces. The first practical step is to identify all instances of FastapiAdmin within your environment, confirm their network exposure and business criticality, and then assign ownership for remediation based on this assessment.

Application owners and platform teams.
Verify FastapiAdmin instances and exposure.
Plan remediation based on risk.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is FastapiAdmin?

FastapiAdmin is an administrative dashboard framework built on the FastAPI web framework. Developers use it to create management interfaces for their applications, providing a graphical way to perform database operations, user management, and other administrative tasks for backend services.

What does CWE-306 mean for CVE-2026-111641?

CWE-306 refers to a Missing Authentication for Critical Function. In this case, the software fails to verify the identity of a user before performing highly sensitive actions, such as generating session tokens. Because the auto-login feature lacks security checks, the system blindly trusts requests, allowing anyone to bypass the intended login process.

How do attackers trigger this authentication bypass?

An attacker targets specific API endpoints intended for auto-login functionality. By interacting directly with these unprotected paths, they can enumerate user accounts and generate valid session tokens for any user, including administrators. Simply accessing the application does not trigger the bug; the attacker must specifically interact with these unauthenticated backend API routes.

Is my instance at risk according to Halo Surface Signal?

Halo Surface Signal notes that FastapiAdmin is often deployed as a web or API management interface, making it a high-visibility target. If your instance is reachable via the internet or accessible across your internal network for remote management, it is likely exposed. The vulnerability is most critical for interfaces accessible to unauthorized users on the network.

What should I do if I run FastapiAdmin?

Start by auditing your environment to locate all active FastapiAdmin deployments. Once identified, evaluate whether these interfaces need to be reachable over the network. If the service is not strictly required, restrict access at the network level immediately while you coordinate with your team to review the authentication configurations and plan for necessary updates.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.