CVE-2026-46440: Flowiseai Flowise Auth Bypass Flaw

CVE-2026-46440 Overview

CVE-2026-46440 is a credential handling vulnerability in Flowise, a drag-and-drop interface for building large language model (LLM) workflows. The flaw resides in the checkBasicAuth endpoint, which validates credentials in plaintext using direct string comparison and lacks rate limiting. Attackers can remotely brute-force or replay credentials against exposed Flowise instances without triggering lockouts. The issue affects all versions prior to 3.1.2 and is tracked under [CWE-522: Insufficiently Protected Credentials]. The vendor patched the vulnerability in Flowise release 3.1.2.

Critical Impact
Unauthenticated network attackers can perform unlimited credential guessing against the checkBasicAuth endpoint, leading to full takeover of Flowise instances and the LLM pipelines they orchestrate.

Affected Products

FlowiseAI Flowise versions prior to 3.1.2
Self-hosted Flowise deployments exposing the authentication endpoint to untrusted networks
Containerized Flowise instances using default basic authentication

Discovery Timeline

2026-06-08 - CVE-2026-46440 published to the National Vulnerability Database (NVD)
2026-06-11 - Last updated in NVD database

Technical Details for CVE-2026-46440

Vulnerability Analysis

Flowise exposes a checkBasicAuth endpoint used to validate HTTP Basic Authentication credentials submitted by clients. In versions before 3.1.2, this endpoint performs validation using direct plaintext comparison of the supplied credentials against stored values. The endpoint does not enforce rate limiting, account lockout, or progressive delays between authentication attempts.

The combination of these two weaknesses allows attackers to submit credential guesses at the maximum rate the server can process. Because comparisons are direct rather than constant-time, the implementation may also leak timing information that accelerates credential discovery. Successful authentication grants full administrative access to Flowise chatflows, API keys, and any integrated LLM provider credentials.

Root Cause

The root cause is insufficiently protected credentials [CWE-522]. The checkBasicAuth handler combines two design flaws: storage and comparison of credentials in plaintext, and the absence of throttling middleware on the authentication path. Both flaws compound to remove the practical cost of online brute-force attacks.

Attack Vector

The attack is network-based, requires no privileges, and requires no user interaction. An attacker enumerates valid usernames or attempts common passwords against the Flowise basic authentication endpoint over HTTP or HTTPS. Without rate limiting, automated tooling can iterate through large credential dictionaries until valid credentials are found. Once authenticated, the attacker can exfiltrate stored API keys, modify LLM chatflows, or pivot to connected services such as OpenAI, vector databases, or internal APIs configured within Flowise.

No verified public proof-of-concept code is available. See the GitHub Security Advisory GHSA-php6-83fg-gw3g for vendor-provided technical details.

Detection Methods for CVE-2026-46440

Indicators of Compromise

High volume of HTTP requests to the Flowise checkBasicAuth endpoint from a single source IP within a short time window
Sequential authentication failures followed by a successful 200 response without prior legitimate session activity
Unexpected changes to chatflows, credentials, or API keys in Flowise audit logs
Outbound connections from Flowise to unfamiliar LLM provider endpoints or data destinations

Detection Strategies

Inspect web server and reverse proxy logs for repeated Authorization: Basic headers targeting Flowise authentication routes
Correlate failed-to-successful authentication transitions on the Flowise host to identify successful brute-force outcomes
Alert on Flowise process activity that spawns shells, network scanners, or modifies configuration files outside of upgrade windows

Monitoring Recommendations

Forward Flowise application and reverse proxy logs to a centralized SIEM for behavioral analysis
Establish baseline authentication request rates per source IP and alert on deviations
Monitor egress from Flowise hosts for connections to unsanctioned third-party APIs or LLM providers

How to Mitigate CVE-2026-46440

Immediate Actions Required

Upgrade Flowise to version 3.1.2 or later immediately
Rotate all credentials, API keys, and LLM provider tokens stored within Flowise after patching
Restrict network exposure of Flowise to trusted networks or place it behind an authenticated reverse proxy or VPN
Audit Flowise chatflows and configuration for unauthorized modifications since the deployment date

Patch Information

The vendor released the fix in Flowise 3.1.2. The patch addresses the plaintext credential comparison and introduces protections on the checkBasicAuth endpoint. Administrators should review the GitHub Security Advisory GHSA-php6-83fg-gw3g for upgrade guidance.

Workarounds

Place Flowise behind a reverse proxy such as nginx or Traefik that enforces rate limiting and IP allowlisting on authentication routes
Require an additional authentication layer such as mutual TLS, OAuth, or an identity-aware proxy before traffic reaches Flowise
Disable internet exposure of Flowise management interfaces and restrict access to internal VLANs or VPN-only segments
Enforce strong, unique passwords with high entropy for any Flowise administrative account until the upgrade is complete

bash

# Example nginx rate limit for the Flowise auth endpoint
limit_req_zone $binary_remote_addr zone=flowise_auth:10m rate=5r/m;

server {
    listen 443 ssl;
    server_name flowise.example.com;

    location /api/v1/ {
        limit_req zone=flowise_auth burst=5 nodelay;
        allow 10.0.0.0/8;
        deny all;
        proxy_pass http://127.0.0.1:3000;
    }
}