The vulnerability exists in LobeChat’s Knowledge Base file removal endpoint, which is a tRPC method that lets authenticated users delete files from knowledge bases. The backend query lacks an ownership check because the user‑ID filter is commented out. Without this check, an attacker can delete any file in any knowledge base as long as they supply a valid knowledge‑base ID and file ID. The data loss is not limited to a single user; the attacker can wipe or modify other users’ knowledge base contents, impacting confidentiality and integrity of user data. The vulnerability is classified under CWE-284 (Improper Access Control), CWE-639 (Authorization Bypass Through User-Controlled Key), CWE-862 (Missing Authorization in Resource Access Control), and CWE-915 (Privilege Existence Error), underscoring that it is an access‑control flaw that permits unauthorised deletion.

The issue affects LobeChat versions prior to 2.0.0‑next.193, as supplied by the vendor lobehub. Users running any earlier release of this open‑source chat application platform are at risk because the IDOR exists in the mentioned endpoint.

The CVSS score is 3.7, indicating moderate severity, while the EPSS score is less than 1%, meaning current exploitation probability is very low. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. Practically, exploitation requires knowledge of the target knowledge‑base ID and file ID. These IDs are randomly generated and not easily enumerated, but may leak through shared links, logs, or referrer headers. Even with low likelihood, the missing authorization check makes this a critical security flaw because it allows any authenticated user to delete another user’s files if the identifiers are known.