An input validation flaw was discovered in how multiple OpenStack services validate images with backing file references. An authenticated attacker could provide a malicious image via upload, or by creating and modifying an image from an existing volume. Validation of images can be triggered during image upload or when attaching images to virtual machines. During this process, the affected OpenStack services could be tricked into reading or writing to the host with the equivalent privileges of QEMU. This bypasses isolation restrictions, significantly reducing the security of an affected compute host, and could enable arbitrary code execution, a denial of service, or leaking of secrets. If exploited, the immediate impact is limited to an individual compute host. However, if the attacker has access to multiple hosts and enough time to repeat it, they could potentially spread across all compute hosts.