An issue was discovered in OpenStack Nova before 30.2.2, 31 before 31.2.1, and 32 before 32.1.1. By writing a malicious QCOW header to a root or ephemeral disk and then triggering a resize, a user may convince Nova's Flat image backend to call qemu-img without a format restriction, resulting in an unsafe image resize operation that could destroy data on the host system. Only compute nodes using the Flat image backend (usually configured with use_cow_images=False) are affected.

OpenStack Nova before 2012.1 allows someone with access to an EC2_ACCESS_KEY (equivalent to a username) to obtain the EC2_SECRET_KEY (equivalent to a password). Exposing the EC2_ACCESS_KEY via http or tools that allow man-in-the-middle over https could allow an attacker to easily obtain the EC2_SECRET_KEY. An attacker could also presumably brute force values for EC2_ACCESS_KEY.