MaxKB’s OSS file service URL fetch API (chat/api/oss/get_url) accepts an application_id from the URL path without verifying that the caller owns or is authorized for that application. This allows an attacker who can reach the endpoint to perform actions that are normally restricted to the owning application’s users, effectively bypassing the intended access controls. The flaw can lead to unauthorized retrieval or manipulation of data that should remain isolated to a single application, compromising data integrity and confidentiality.

The vulnerability affects the open‑source AI assistant MaxKB produced by 1Panel-dev. Versions 2.8.0 and all earlier releases are vulnerable; the issue was fixed in release 2.8.1.

The CVSS score is 5.3, indicating a moderate severity. The EPSS score is not available, and the vulnerability is not listed in the CISA KEV catalog. Attackers can exploit the flaw by accessing the chat/api/oss/get_url endpoint with a manipulated application_id, provided they have network reach to the server and any required authentication. No advanced conditions or exploits are required to leverage this weakness. The risk is primarily in the accidental or malicious misuse of the URL fetch operation by users or applications that should not have cross‑application permissions.