The vulnerability is an Insecure Direct Object Reference that allows any authenticated user to overwrite another user’s API keys via the PUT /api/keys endpoint. It is enabled by the JavaScript object spread operator that overwrites the authenticated user’s identifier, allowing injection of a userId in the request body. The attacker can replace a victim’s keys for OpenAI, Anthropic, Azure, or similar services, redirecting conversations or causing denial of service. The weakness is classified as CWE‑862. The impact is loss of confidentiality and integrity of third‑party API usage and disruption of service for the victim user.

The affected product is LibreChat from the vendor danny‑avila, in all releases up to and including version 0.7.6. The vulnerability is patched in version 0.8.3‑rc1. Versions beyond 0.8.3‑rc1 are not affected.

The CVSS score of 7.1 indicates medium‑to‑high severity. The EPSS score is not available, and the vulnerability is not yet listed in CISA KEV. The integration of the IDOR is limited to authenticated users, who can supply any userId in the request body. A successful exploit allows overwriting of another user’s API keys, potentially steering conversations to attacker‑controlled services or causing denial of service. The upstream example also indicates that the attack does not require elevated privileges beyond a valid user account. The attack vector is a direct API call, so network penetration is not required.