CVE-2021-41641: Link Following in Deno

The vulnerability stems from improper permission checks in symbolic link creation. The commit d44011a shows both sync()/async() symlink functions were modified to require full read/write permissions (check_all()) instead of path-specific checks. This indicates the original implementation only verified write access to the target path, not system-wide permissions, allowing attackers to create symlinks in permitted directories that point to restricted locations. The CVE description explicitly mentions Deno.symlink as the exploitation vector, and the patch confirms the functions' security logic was inadequate pre-1.16.0.