LibreChat allows any authenticated user to upload files through the /api/files/images endpoint without verifying permission on the target agent. The missing authorization check means a user can place malicious or arbitrary files into an agent's tool_resources, potentially altering the agent's behavior or enabling further attacks. This flaw is classified as an Authorization Bypass vulnerability (CWE-862).

The vulnerability affects the LibreChat application developed by danny-avila. Any deployment running a version earlier than 0.8.4-rc1 is susceptible, as the fix that added permission checks to the generic file upload endpoint was never applied to the image upload route.

The CVSS score of 6.5 indicates moderate severity. Since the EPSS score is not available and the issue is not listed in the CISA KEV, the public exploitation probability is unclear, yet the flaw can be leveraged by any authenticated user. An attacker can use the image upload endpoint to bypass necessary checks and place files that an agent will later consume, potentially leading to data leakage or execution of malicious code within the agent's environment. The ease of use of the HTTP endpoint means exploitation requires minimal expertise beyond legitimate authentication credentials.