LibreChat’s isPrivateIP() function incorrectly ignores IPv4-mapped IPv6 addresses in their hex‑normalized form, allowing authenticated users to manipulate the server into making outbound HTTP requests to internal addresses. This bypass enables the attacker to access internal resources such as cloud metadata services, loopback interfaces, or RFC1918 networks, potentially leaking confidential data or facilitating further attacks.

The issue affects the LibreChat application from the vendor danny-avila. All releases prior to version 0.8.3 are vulnerable. Version 0.8.3 and later include a fix that properly detects IPv4‑mapped IPv6 addresses.

The CVSS score of 8.5 indicates a high severity vulnerability. While the EPSS score is not available and the CVE is not listed in the CISA KEV catalog, exploitation requires an authenticated user and can directly expose internal network services. The vulnerability’s impact is significant, permitting arbitrary internal requests that can lead to data disclosure, credential leakage, or further compromise of the internal network.