Kata Containers: Config Path Annotation Arbitrary File Loading

Kata Containers is an open source project focusing on a standard implementation of lightweight Virtual Machines (VMs) that perform like containers. Prior to version 4.0.0, kata-runtime is vulnerable to host code execution via an unvalidated configuration path annotation. The runtime accepts an arbitrary io.katacontainers.config_path pod annotation and loads the referenced host TOML file without restriction. As a result, a pod user who can place a file at a host-visible path can supply a configuration that selects an attacker-controlled hypervisor or virtio-fs daemon binary, executing code as root on the host. This issue is fixed in version 4.0.0.

Kata Containers: Unauthorized mem-agent ttRPC methods let an untrusted host tamper with confidential-guest memory

Kata Containers is an open source implementation of lightweight Virtual Machines (VMs) that perform like containers. In versions prior to 4.0.0, the kata-agent is vulnerable to an authorization bypass in confidential-guest memory management. In Confidential Containers (CoCo) deployments, the kata-agent enforces an OPA/Rego-based AgentPolicy that must authorize every ttRPC API call, forming the security boundary that prevents an untrusted host from directing the confidential guest. Two ttRPC methods introduced with the mem-agent feature are missing this authorization check, so an untrusted host can invoke them unconditionally regardless of the guest's policy configuration. When mem-agent is enabled (off by default), this lets the host tamper with in-guest memory management by forcing swap, aggressive eviction, or compaction, resulting in attacker-controlled availability and performance degradation of the confidential workload entirely outside the agent-policy boundary. The impact does not include memory disclosure or code execution, and severity is bounded by the precondition that mem-agent must be explicitly enabled. This issue is fixed in version 4.0.0.

Kata guest escape: runtime-rs guest-root to host-root escape via virtiofs

Kata Containers is an open source project focusing on a standard implementation of lightweight Virtual Machines (VMs) that perform like containers. Prior to 3.31.0, the runtime-rs standalone virtio-fs path is vulnerable to a guest-root to host-root escape. In this configuration, Kata runs the host virtiofsd as root with --sandbox none --seccomp none, so an attacker with root-equivalent access inside the guest can bypass the guest virtio-fs client entirely by taking over the virtio-fs PCI device and building a virtqueue in userspace to submit raw FUSE requests directly to the host virtiofsd. A crafted FUSE_SYMLINK request whose new symlink name is an absolute host path is honored outside the configured shared directory, allowing guest root to create root-owned symlinks in sensitive host locations such as /etc/cron.d. By pointing such a symlink at a guest-controlled crontab payload reachable through a live runtime process's mount namespace, the attacker causes the host cron daemon to execute that payload as host root, crossing the Kata isolation boundary. This issue is fixed in version 3.31.0.

Kata Containers have VM Escape via virtiofsd Argument Injection through Default-Enabled Pod Annotations

Kata Containers is an open source project focusing on a standard implementation of lightweight Virtual Machines (VMs) that perform like containers. Versions prior to 3.31.0 ship with a default configuration that allows pod creators to inject arbitrary command-line arguments into the virtiofsd process through the `io.katacontainers.config.hypervisor.virtio_fs_extra_args` pod annotation. By injecting `-o source=/` along with `--no-announce-submounts` and `--sandbox=none`, an attacker can override the virtiofsd shared directory to serve the entire host root filesystem into the guest VM. Combined with the `kernel_params` annotation (also enabled by default) to activate the agent debug console, the attacker can mount the host filesystem from inside the VM and read or write any file on the host, including /etc/shadow. Version 3.31.0 patches the issue.

Kata Containers: CopyFile Policy Subversion via Symlinks

Kata Containers is an open source project focusing on a standard implementation of lightweight Virtual Machines (VMs) that perform like containers. From v3.4.0 to v3.28.0, an oversight in the CopyFile policy (and perhaps the CopyFile handler) allows untrusted hosts to write to arbitrary locations inside the guest workload image. This can be used to overwrite binaries inside the guest and exfiltrate data from containers; even those running inside CVMs. This vulnerability is fixed in v3.29.0.

Kata Container to Guest micro VM privilege escalation

Kata Containers is an open source project focusing on a standard implementation of lightweight Virtual Machines (VMs) that perform like containers. In versions prior to 3.27.0, an issue in Kata with Cloud Hypervisor allows a user of the container to modify the file system used by the Guest micro VM ultimately achieving arbitrary code execution as root in said VM. The current understanding is this doesn’t impact the security of the Host or of other containers / VMs running on that Host (note that arm64 QEMU lacks NVDIMM read-only support: It is believed that until the upstream QEMU gains this capability, a guest write could reach the image file). Version 3.27.0 patches the issue.

Kata Containers Runtime: Host block device can be hotplugged to the VM if the container image is malformed or contains no layers

Kata Containers is an open source project focusing on a standard implementation of lightweight Virtual Machines (VMs) that perform like containers. In versions prior to 3.26.0, when a container image is malformed or contains no layers, containerd falls back to bind-mounting an empty snapshotter directory for the container rootfs. When the Kata runtime attempts to mount the container rootfs, the bind mount causes the rootfs to be detected as a block device, leading to the underlying device being hotplugged to the guest. This can cause filesystem-level errors on the host due to double inode allocation, and may lead to the host's block device being mounted as read-only. Version 3.26.0 contains a patch for the issue.

Kata Containers coco-tdx malicious host can circumvent initdata verification

Kata Containers is an open source project focusing on a standard implementation of lightweight Virtual Machines (VMs) that perform like containers. In Kata Containers versions from 3.20.0 and before, a malicious host can circumvent initdata verification. On TDX systems running confidential guests, a malicious host can selectively fail IO operations to skip initdata verification. This allows an attacker to launch arbitrary workloads while being able to attest successfully to Trustee impersonating any benign workload. This issue has been patched in Kata Containers version 3.21.0.

Kata Containers - Guests can trick the kata-runtime into mounting the container image on any host path

A malicious guest compromised before a container creation (e.g. a malicious guest image or a guest running multiple containers) can trick the kata runtime into mounting the untrusted container filesystem on any host path, potentially allowing for code execution on the host. This issue affects: Kata Containers 1.11 versions earlier than 1.11.1; Kata Containers 1.10 versions earlier than 1.10.5; Kata Containers 1.9 and earlier versions.

Kata Containers - Cloud Hypervisor guests persist filesystem changes to the underlying host image file

Kata Containers before 1.11.0 on Cloud Hypervisor persists guest filesystem changes to the underlying image file on the host. A malicious guest can overwrite the image file to gain control of all subsequent guest VMs. Since Kata Containers uses the same VM image file with all VMMs, this issue may also affect QEMU and Firecracker based guests.

Kata Containers - Guests can trick the kata-runtime into unmounting any mount point on the host

An improper link resolution vulnerability affects Kata Containers versions prior to 1.11.0. Upon container teardown, a malicious guest can trick the kata-runtime into unmounting any mount point on the host and all mount points underneath it, potentiality resulting in a host DoS.

Kata Containers - Containers have access to the guest root filesystem device

Kata Containers doesn't restrict containers from accessing the guest's root filesystem device. Malicious containers can exploit this to gain code execution on the guest and masquerade as the kata-agent. This issue affects Kata Containers 1.11 versions earlier than 1.11.1; Kata Containers 1.10 versions earlier than 1.10.5; and Kata Containers 1.9 and earlier versions.

An improper file permissions vulnerability affects Kata Containers prior to 1.11.5. When using a Kubernetes hostPath volume and mounting either a file or directory into a container as readonly, the file/directory is mounted as readOnly inside the container, but is still writable inside the guest. For a container breakout situation, a malicious guest can potentially modify or delete files/directories expected to be read-only.

An issue was discovered in Kata Containers through 1.11.3 and 2.x through 2.0-rc1. The runtime will execute binaries given using annotations without any kind of validation. Someone who is granted access rights to a cluster will be able to have kata-runtime execute arbitrary binaries as root on the worker nodes.