Executive Summary

The CVE-2026-46440 vulnerability in FlowiseAI/Flowise involves a Basic Auth endpoint called `checkBasicAuth` that validates credentials in plaintext without proper security measures.

This endpoint directly compares plaintext usernames and passwords against environment variables without hashing or using constant-time comparison, making it vulnerable to timing attacks.

It also returns distinct success or failure messages, which enables attackers to enumerate valid credentials.

Additionally, there is no rate limiting on this endpoint, allowing unlimited brute-force attempts.

This vulnerability was patched in version 3.1.2 of Flowise.

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Compliance Impact

The vulnerability in FlowiseAI/Flowise exposes plaintext credentials without proper security measures, allowing unauthorized access through brute-force and timing attacks. This compromises confidentiality, integrity, and availability of sensitive information.

Such exposure and unauthorized access risks violating common standards and regulations like GDPR and HIPAA, which require protection of personal and sensitive data through strong authentication, encryption, and access controls.

Failure to secure authentication endpoints as described could lead to non-compliance with these regulations, potentially resulting in data breaches, legal penalties, and loss of trust.

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Impact Analysis

Successful exploitation of this vulnerability could grant unauthorized access to the Flowise application.

Because the endpoint lacks rate limiting and uses insecure credential validation, attackers can perform brute-force attacks to discover valid credentials.

This impacts the confidentiality, integrity, and availability of the application, as indicated by the high CVSS score of 7.5.

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Detection Guidance

The vulnerability involves the `checkBasicAuth` endpoint exposing plaintext credential validation without rate limiting and with direct comparison, which can be detected by monitoring for repeated authentication attempts and distinct success/failure messages.

To detect exploitation attempts on your system or network, you can look for unusual patterns of repeated login attempts to the `checkBasicAuth` endpoint, which may indicate brute-force attacks.

• Use network monitoring tools (e.g., Wireshark or tcpdump) to capture HTTP requests targeting the `checkBasicAuth` endpoint and analyze for repeated authentication attempts.
• Check application logs for multiple failed authentication attempts without rate limiting.
• Example command to monitor HTTP requests to the endpoint using tcpdump: `tcpdump -i any -A 'tcp port 80 and (((ip[2:2] - ((ip[0]&0xf)<<2)) - ((tcp[12]&0xf0)>>2)) != 0)' | grep 'checkBasicAuth'`
• Use curl or similar tools to test the endpoint manually and observe if distinct success/failure messages are returned, e.g., `curl -i -X POST http://<host>/checkBasicAuth -d 'username=test&password=test'`.

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Mitigation Strategies

Immediate mitigation steps include upgrading Flowise to version 3.1.2 or later, where this vulnerability has been patched.

If upgrading is not immediately possible, consider implementing the following temporary measures:

• Add rate limiting to the `checkBasicAuth` endpoint to prevent unlimited brute-force attempts.
• Modify the authentication logic to use constant-time comparison and hash credentials instead of plaintext comparison.
• Change the endpoint to return generic error messages instead of distinct success/failure responses to prevent credential enumeration.
• Enable logging and monitoring of failed authentication attempts to detect potential attacks.

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