This vulnerability involves an out-of-bounds write in the virtio PCI transport component of AWS Firecracker microVMs, affecting versions 1.13.0 through 1.14.3 and 1.15.0 on both x86_64 and aarch64 platforms. The flaw allows a local guest user with root privileges to corrupt memory by modifying virtio queue configuration registers after device activation, potentially causing a denial of service by crashing the VMM process or enabling arbitrary code execution on the host. However, successful code execution requires additional preconditions such as use of a custom guest kernel or specific snapshot configurations. AWS has addressed the issue by releasing Firecracker versions 1.14.4 and 1.15.1 and later. As Firecracker is offered as a cloud service, AWS manages patching for hosted environments. The CVSS v3.1 base score is 7.5, reflecting high severity with impact on confidentiality, integrity, and availability.

A local guest user with root privileges inside a Firecracker microVM can exploit this vulnerability to crash the Firecracker VMM process, causing denial of service. Under certain conditions, such as a custom guest kernel or specific snapshot configurations, the attacker may achieve arbitrary code execution on the host system, potentially compromising host confidentiality, integrity, and availability. No known active exploits have been reported.

AWS has released fixed versions of Firecracker (1.14.4 and 1.15.1 and later) that address this vulnerability. Users should upgrade to these versions to remediate the issue. Since Firecracker is a cloud-hosted service, AWS manages remediation for hosted environments. Refer to the AWS security bulletin at https://aws.amazon.com/security/security-bulletins/2026-015-aws/ for official guidance and confirmation of patch status.