In Firecracker 0.20.x before 0.20.1 and 0.21.x before 0.21.2, the network stack can freeze under heavy ingress traffic. This can result in a denial of service on the microVM when it is configured with a single network interface, and an availability problem for the microVM network interface on which the issue is triggered.

In Amazon AWS Firecracker before 0.21.3, and 0.22.x before 0.22.1, the serial console buffer can grow its memory usage without limit when data is sent to the standard input. This can result in a memory leak on the microVM emulation thread, possibly occupying more memory than intended on the host.