A vulnerability dubbed “CopyEscape” in Docker lets malicious containers overwrite files on the host system – and, in some cases, execute code with root privileges. Docker has since fixed the flaw (CVE-2026-17106).
Escaping via “docker cp”
The vulnerability sits in Docker’s archive library moby/go-archive and occurs when copying with the “docker cp” command. Through a so-called TOCTOU race condition (time-of-check to time-of-use) during the file-walking stage, a malicious container can create or overwrite files outside the intended destination – on the machine running the Docker CLI.
From container to host root
If the escape succeeds, host files can be overwritten and, in certain configurations, code can be executed with root privileges. That breaks the isolation between container and host – the nightmare of any container environment.
Updates available
The issue is fixed in Docker Engine and CLI 29.7.2, Docker Desktop 4.86.0 and Docker Sandboxes 0.38.0. Anyone running Docker – in the homelab or in production – should update promptly.
