FastGPT versions before 4.15.0-beta5 contain an authorization bypass vulnerability (CWE-639) where two file handlers authorize unrelated resources but then sign or read S3 objects using keys directly from user requests without verifying that the key belongs to the caller's team. Because S3 object keys are global within the bucket and tenant identification is only part of the path, an attacker can supply another team's key to access their files through the chat-file presign or dataset preview endpoints. This vulnerability allows unauthorized read access to other tenants' files. The issue is resolved in FastGPT version 4.15.0-beta5. The CVSS 3.1 score is 8.6 (high severity) with network attack vector, low complexity, no privileges required, no user interaction, and impact on confidentiality only.

An attacker can bypass authorization controls to read files belonging to other teams by supplying their S3 object keys, leading to unauthorized disclosure of sensitive data stored in the FastGPT platform. The vulnerability affects confidentiality but does not impact integrity or availability. There are no known exploits in the wild. Because the service is cloud-hosted, the vendor manages remediation.

This vulnerability is fixed in FastGPT version 4.15.0-beta5. Since FastGPT is a cloud service, the vendor typically manages remediation server-side. Users should verify with the vendor advisory that their service instance is updated to version 4.15.0-beta5 or later to ensure the vulnerability is mitigated. Patch status is confirmed as fixed in v4.15.0-beta5.