Podman: kernel: containers in shared ipc namespace are vulnerable to denial of service attack

Vulnerability

A flaw in Podman allows a malicious container sharing an IPC namespace with other containers to create a large number of IPC resources in /dev/shm, exhausting memory until the container is OOM-killed. The IPC resources persist because they are tied to the IPC namespace, which remains open as long as any container using it is running. When the malicious container restarts (automatically or by attacker control), it repeats the process, accumulating memory consumption over time [1][4].

Exploitation

An attacker must have the ability to run a container with shared IPC (e.g., --ipc=shareable or pod-based setups) and configure it to restart automatically (e.g., --restart=always). The malicious container repeatedly creates IPC resources until OOM, then restarts, each cycle leaking memory that is not freed because the cgroup is removed but the IPC resources remain accounted to the namespace [3][4].

Impact

This can lead to a memory-based denial of service on the host system, potentially affecting all containers and services. The attack requires no special privileges beyond container runtime access and can persist indefinitely if the malicious container is set to always restart [1][3].

Mitigation

As of the report, no patch is available for affected versions (Podman 5.0.0-dev and earlier). Users should avoid sharing IPC namespaces between untrusted containers, implement memory limits via cgroups, and consider using --restart=on-failure instead of --restart=always to prevent automatic restarts [4].