CVE-2026-54027: LibreChat file upload authorization bypass through image upload endpoint

Summary

LibreChat versions prior to 0.8.4-rc1 let any authenticated user upload files into any agent's tool_resources (such as context and execute_code) through the POST /api/files/images endpoint. This route lacks the ownership and EDIT permission check that POST /api/files received in an earlier patch, so an attacker can bypass that authorization by using the image endpoint instead.

Mitigation

Fixed in 0.8.4-rc1.

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