AIKIDO-2026-77238

firecracker is vulnerable to Guest Access to Host Process Memory

CVE-2026-122192Published 3 days ago

CVE Score

High

Guest Access to Host Process Memory

TL;DR

Affected versions of Firecracker can let a root user in a guest read or modify memory of the Firecracker process after a failed guest memory discard. When replacement of a discarded memory mapping fails, Firecracker continues running with part of the guest memory range unmapped. Memory later allocated there by Firecracker can become accessible to the guest, compromising isolation.

How do I fix this?

Upgrade firecracker to 1.16.2, 1.17.0 or later. The fix preserves the original mapping's MAP_NORESERVE flag and terminates Firecracker and its VM if a replacement mapping fails. If you cannot upgrade immediately, restore snapshots using the Uffd memory backend and follow its documented requirements for handling discarded pages. Host memory overcommit and OOM killer settings can reduce exposure but do not fully address the issue.

Who does this affect?

You are affected if you use Firecracker 0.23.0 through 1.16.1, restore VMs from snapshots using the File memory backend, and configure a balloon or virtio-mem device. Exploitation requires root privileges in the guest and host memory conditions that cause replacement of a discarded memory mapping to fail. VMs started without a snapshot or restored using the Uffd memory backend are not affected.