CVE-2026-63764 describes an SSRF vulnerability in the lmdeploy API server by InternLM. Attackers can send a POST request to the chat completions endpoint with an image_url parameter pointing initially to an attacker-controlled server. This server responds with an HTTP 302 redirect to internal network addresses such as loopback interfaces or cloud instance metadata endpoints. The server follows these redirects without reapplying URL safety validation, enabling attackers to access internal services and sensitive metadata endpoints without authentication.

The vulnerability allows unauthenticated remote attackers to access internal network services and cloud metadata endpoints that are normally protected from external access. This can lead to information disclosure and potentially further compromise of the internal environment. The CVSS 4.0 score of 9.2 indicates a critical severity with network attack vector, no privileges or user interaction required, and high impact on confidentiality and integrity.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, restrict access to the vulnerable API server and monitor for suspicious requests involving the image_url parameter. Consider implementing additional validation to prevent following unsafe redirects or disabling redirect following on the image_url fetch functionality.