Three lines of bash escape Docker's Mac hypervisor: CVE-2026-77179 patched in Docker Desktop 4.88.0
blaizedsouza · x · 2026-09-19
Security researcher Oren Yomtov disclosed a sandbox escape in Docker's hypervisor for Mac: a container gains full read/write access to the host filesystem with three lines of bash. Assigned CVE-2026-77179, fixed in Docker Desktop 4.88.0 and Docker Sandboxes 0.42.0.
Root cause: When mounting a folder, Docker VMM uses virtio-fs with the file server on the host. After the first path lookup, the guest addresses files by nodeid, and the server relocates the file on every request — first by inode via macOS volfs, falling back to the saved path string. A guest can open a file, delete it while holding the handle (killing the volfs path), then replace the parent folder with a symlink: the server validates the string as still inside the mount, but the kernel follows the symlink and opens any file on the host.
Why it matters: Docker Desktop is only affected with Docker VMM enabled — which was scheduled to become the default at the end of October 2026, so the timing of the disclosure is fortunate.
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