TLDR Tech / InfoSec
SharedRoot; Escaping the Claude Cowork sandbox
A Claude Cowork session on macOS can chain a user-namespace feature, a Linux traffic-control module, and a recent kernel bug to escalate from an unprivileged VM user to guest root and then write directly to the host filesystem via a shared / mount. The write primitive comes from CVE-2026-46331 in act_pedit, and the path persists as similar bugs appear. To harden the environment, disable unprivileged user namespaces, tighten seccomp, block unneeded autoloaded modules and helper binaries, and scope or remove the host filesystem share so guest-root cannot touch SSH keys or other sensitive data.
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