A critical authorization bypass in MaxKB allows unauthenticated attackers to expose private user conversations and sensitive files by exploiting improper validation of chat session ownership.

The application fails to perform adequate authorization checks on the POST /chat/api/{application_id}/chat/{chat_id}/share_chat endpoint. This allows an attacker to bypass security controls and generate public access links for conversations and files they do not own, even without proper authentication.

The exploitation of this flaw leads to the unauthorized disclosure of sensitive enterprise data contained within AI-assisted conversations. Because the vulnerability allows for the creation of persistent public links without a revocation path, the business faces significant risks regarding data privacy, compliance violations, and the exposure of proprietary information. The CVSS score of 6.5 reflects a medium severity, but the impact is compounded by the potential for permanent data leakage.

Immediate Action: As no official patch is currently available, administrators should restrict access to the affected MaxKB instances by placing them behind a secure VPN or an authenticated proxy.

Proactive Monitoring: Review web access logs for unusual patterns of POST requests to the /chat/api/ endpoint, particularly those involving unexpected chat_id parameters.

Compensating Controls: Implement Web Application Firewall (WAF) rules to filter and block requests to the vulnerable share_chat API path from untrusted sources.

Public Exploit Available: Unknown

Organizations utilizing MaxKB must treat this vulnerability with high urgency due to the permanent nature of the data exposure it facilitates. Until the vendor releases a security update, immediate network-level isolation of the application is required to prevent unauthorized access. Administrators should monitor the official GitHub repository for the release of a fixed version and apply it immediately upon availability.