CVE-2026-3693: Shy2593666979 AgentChat RCE Vulnerability

CVE-2026-3693 Overview

A vulnerability has been identified in Shy2593666979 AgentChat up to version 2.3.0 involving improper control of resource identifiers (CWE-99). This flaw affects the get_user_info and update_user_info functions within the /src/backend/agentchat/api/v1/user.py file of the User Endpoint component. By manipulating the user_id argument, an attacker can exploit improper resource identifier handling to access or modify unauthorized resources.

Critical Impact

Remote attackers can manipulate the user_id parameter to access or modify user information belonging to other accounts, potentially leading to unauthorized data access and privilege abuse.

Affected Products

• Shy2593666979 AgentChat versions up to 2.3.0
• AgentChat User Endpoint component (/src/backend/agentchat/api/v1/user.py)

Discovery Timeline

• March 8, 2026 - CVE-2026-3693 published to NVD
• March 9, 2026 - Last updated in NVD database

Technical Details for CVE-2026-3693

Vulnerability Analysis

This vulnerability stems from improper control of resource identifiers in the AgentChat application's user management functionality. The affected functions get_user_info and update_user_info fail to properly validate and sanitize the user_id parameter before using it to access or modify user resources. This allows remote attackers to manipulate the identifier to reference resources belonging to other users, effectively bypassing authorization controls.

The vulnerability is remotely exploitable without requiring authentication or user interaction. An attacker with network access to the AgentChat application can craft malicious requests targeting the User Endpoint to enumerate user information or perform unauthorized modifications to user accounts.

Root Cause

The root cause is insufficient validation of the user_id argument in the user management API endpoints. The application does not properly verify that the requesting user has authorization to access or modify the specified user resource, nor does it adequately sanitize the input to prevent resource identifier manipulation.

Attack Vector

The attack can be initiated remotely over the network. An attacker crafts HTTP requests to the User Endpoint (/src/backend/agentchat/api/v1/user.py) with manipulated user_id values to access or modify user information for accounts they should not have access to.

The vulnerability allows attackers to modify the user_id parameter in requests to the get_user_info and update_user_info endpoints. By iterating through or guessing valid user identifiers, an attacker can retrieve sensitive user information or alter user account details without proper authorization. Technical details and proof-of-concept examples are available in the vulnerability disclosure repository.

Detection Methods for CVE-2026-3693

Indicators of Compromise

• Unusual patterns of requests to /api/v1/user endpoints with sequential or varied user_id parameters
• Access logs showing a single source IP querying multiple different user IDs in rapid succession
• Failed authorization events or access attempts to user resources outside normal application behavior

Detection Strategies

• Monitor HTTP request logs for anomalous patterns targeting user endpoints with varying user_id parameters
• Implement rate limiting and alerting on excessive requests to user information endpoints
• Deploy web application firewall (WAF) rules to detect parameter manipulation attempts on user-related API calls
• Review application logs for unauthorized access attempts to user resources

Monitoring Recommendations

• Enable detailed logging for all User Endpoint API calls including the user_id parameter values
• Set up alerts for failed authorization attempts on user management functions
• Implement anomaly detection for unusual access patterns to user data endpoints

How to Mitigate CVE-2026-3693

Immediate Actions Required

• Restrict network access to the AgentChat application to trusted sources only
• Implement additional authorization checks at the API gateway or reverse proxy level
• Review and audit recent access logs for signs of exploitation
• Consider temporarily disabling the affected user management endpoints until a patch is available

Patch Information

No official patch information is currently available. The vendor was contacted early about this disclosure but did not respond. Organizations should monitor the VulDB entry and vendor channels for updates regarding security fixes.

Workarounds

• Implement server-side authorization checks to ensure users can only access their own user information
• Add input validation to sanitize and verify user_id parameters against the authenticated user's session
• Deploy network-level access controls to limit exposure of the AgentChat application
• Use a web application firewall to filter and block suspicious parameter manipulation attempts

# Example: Restrict access to user endpoints via nginx
location /api/v1/user {
    # Limit access to trusted IP ranges
    allow 10.0.0.0/8;
    allow 192.168.0.0/16;
    deny all;
    
    # Rate limiting
    limit_req zone=user_api burst=5 nodelay;
    
    proxy_pass http://agentchat_backend;
}