A flaw in the Feast Feature Server’s /save-document endpoint permits an unauthenticated user to write arbitrary JSON files onto the server’s filesystem. The application’s intended file location restrictions can be bypassed, allowing an attacker to overwrite critical configuration files or startup scripts. This can result in unauthorized system modifications, denial of service through disk exhaustion, or even remote code execution if executable scripts are overwritten.

All deployments of the Feast Feature Server are potentially affected. The vulnerability targets the /save-document functionality and no specific product versions are disclosed, so any instance of this component should be treated as at risk.

The CVSS score of 9.1 indicates critical severity, and because no authentication or privilege is required, the risk of exploitation is high for any network‑reachable attacker. The EPSS score is not available, but the lack of credentials or special permissions strongly suggests a high likelihood of exploitation. The vulnerability is not currently listed in CISA’s catalog of known exploited vulnerabilities, but its characteristics make it a high‑risk target. The likely attack vector is an unauthenticated HTTP request to the /save-document endpoint with minimal prerequisites beyond network access.