Docker Sandbox Escape Exposes macOS Host Files to Guest Code
CVE-2026-77179 reveals a critical container/VM sandbox escape flaw in Docker for macOS, where malicious guest code can break out of its isolated project directory and read or modify any host file accessible to the running user. A companion flaw, CVE-2026-79994, further allows guest processes to connect to unauthorized Unix domain sockets on the host, broadening the attack surface significantly. These vulnerabilities undermine the fundamental security promise of containerization — that guest workloads are isolated from the host. The risk is especially severe in developer environments where Docker often runs with elevated user privileges and access to sensitive files such as SSH keys, credentials, and source code. Both flaws are patched in version 0.42.0, making rapid upgrade essential.
Tactical Insight
Immediate Actions
- Upgrade all macOS Docker Desktop installations to version 0.42.0 or later immediately.
- Audit running containers and Docker-based sandboxes for any signs of unexpected host file access or unusual socket connections.
- Restrict Docker Desktop user accounts to the minimum required privileges until patching is confirmed.
Configuration Hardening
- Enforce strict bind-mount policies to limit which host directories containers are permitted to access.
- Disable or restrict access to Unix domain sockets exposed on the host from within container environments.
- Use macOS system-level controls (e.g., TCC, sandbox profiles) as an additional layer to limit Docker process file access.
Long-Term Improvements
- Integrate container runtime CVE monitoring into your vulnerability management pipeline to catch critical updates within hours of disclosure.
- Establish a tested emergency patching procedure specifically for developer toolchain components such as Docker, which often run with broad user-level privileges.
- Periodically review and minimize host directory and socket mounts in all Docker Compose and container configuration files.