gocracker isolates guest workloads through multiple defense-in-depth layers. Each VM runs inside its own KVM virtual machine with hardware-enforced memory isolation, complemented by host-side sandboxing.

Each guest runs in a separate KVM virtual machine. Guest memory is isolated by hardware (Intel VT-x / AMD-V / ARM VHE). The guest cannot access host memory or other VMs.

The VMM process applies a seccomp BPF filter that restricts the set of system calls available to the host-side VMM code, limiting the attack surface if a guest-triggered bug causes unintended host behavior.

When --jailer on (the default), each VM worker runs inside:

• A chroot jail with only the files needed by that VM.
• A mount namespace so the worker cannot see or modify the host filesystem.
• A PID namespace so the worker cannot signal other host processes.

After setting up namespaces, the jailer drops privileges to a non-root UID/GID. The --uid and --gid flags on gocracker serve control the target identity.

When running under the jailer, the VMM process is placed in a cgroup v2 scope that enforces memory and CPU limits, preventing a single VM from exhausting host resources.

Please do not file public GitHub issues for suspected vulnerabilities.

Report security issues privately to: security@gocracker.dev

Include:

• Affected version or commit hash
• Host OS / kernel version
• Reproduction steps
• Expected vs. actual behavior
• Impact assessment (if known)

Expected response time: acknowledgment within 48 hours, triage within 7 business days. We will coordinate disclosure timing with the reporter.

Security-sensitive areas include:

• Guest memory and vCPU isolation -- KVM ioctl usage, memory slot setup
• Virtio device emulation -- virtio-blk, virtio-net, virtio-rng, virtio-vsock, virtio-balloon; any guest-controlled input parsed by the host
• OCI extraction and build isolation -- layer unpacking, Dockerfile builds
• Jailer and namespace setup -- chroot, mount namespace, PID namespace, cgroup configuration
• API authentication and path validation -- auth token enforcement, trusted directory checks, path traversal prevention
• Snapshot and migration artifacts -- snapshot bundles contain raw memory; ensure they are stored securely and not served to untrusted parties

Security fixes are applied to the latest release only. There is no long-term support for older versions at this time.