Craft CMS is a content management system. In Craft versions 3.5.0 through 4.16.17 and 5.0.0-RC1 through 5.8.21, the save_images_Asset GraphQL mutation can be abused to fetch internal URLs by providing a domain name that resolves to an internal IP address, bypassing hostname validation. When a non-image file extension such as .txt is allowed, downstream image validation is bypassed, which can allow an authenticated attacker with permission to use save_images_Asset to retrieve sensitive data such as AWS instance metadata credentials from the underlying host. This issue is patched in versions 4.16.18 and 5.8.22.