Executive Summary

CVE-2026-56234 is a vulnerability in Capgo versions before 12.128.2 involving the POST /functions/v1/private/validate_password_compliance endpoint.

This endpoint can be accessed using only the public Supabase key without requiring any authentication, making it publicly callable.

The endpoint is CORS-permissive with wildcard origin allowance, meaning it accepts requests from any origin, and it lacks rate limiting or captcha protection.

Because of these weaknesses, attackers can perform automated password spraying and credential stuffing attacks by repeatedly checking credentials without being blocked or throttled.

This can lead to compromise of user accounts, especially if users reuse passwords across services.

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Impact Analysis

This vulnerability can allow attackers to perform large-scale automated attacks to guess or validate user passwords without restriction.

• Attackers can use password spraying and credential stuffing techniques to compromise user accounts.
• Because the endpoint lacks rate limiting and is accessible with only a public key, attackers can make unlimited attempts without being blocked.
• Successful exploitation may lead to unauthorized access to user accounts, especially if users reuse passwords.
• This can result in account takeovers, data breaches, and potential further exploitation of compromised accounts.

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Detection Guidance

This vulnerability can be detected by monitoring requests to the endpoint /functions/v1/private/validate_password_compliance that are made using only the public Supabase key without authentication.

You can look for repeated POST requests to this endpoint from various IP addresses or with different credentials, which may indicate password spraying or credential stuffing attempts.

A possible command to detect such activity using curl could be:

• curl -X POST https://your-capgo-instance/functions/v1/private/validate_password_compliance -H "apikey: <public_supabase_key>" -d '{"email":"[email protected]","password":"password123"}' -v

Monitoring logs for 401 Unauthorized responses from this endpoint can help identify invalid credential attempts.

Additionally, network intrusion detection systems can be configured to alert on high volumes of requests to this endpoint without valid authentication.

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Mitigation Strategies

Immediate mitigation steps include:

• Require authenticated sessions to access the /functions/v1/private/validate_password_compliance endpoint instead of allowing access with only the public Supabase key.
• Implement rate limiting on the endpoint to prevent automated password spraying and credential stuffing attacks.
• Add captcha verification to the endpoint to block automated abuse.
• Consider removing privileged credential checks from this publicly accessible endpoint.

These steps help reduce the risk of account compromise by limiting unauthorized and automated access.

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Compliance Impact

The vulnerability allows attackers to perform password spraying and credential stuffing attacks due to an exposed credential validation endpoint that lacks authentication, rate limiting, and has a permissive CORS policy.

Such attacks can lead to unauthorized access and potential compromise of user accounts, which may result in exposure of personal or sensitive data.

This exposure and potential data compromise could negatively impact compliance with standards and regulations like GDPR and HIPAA, which require protection of user data and implementation of adequate security controls to prevent unauthorized access.

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