FS Permissions Bypass

Summary

A flaw in Node.js’s Permissions model allows attackers to bypass --allow-fs-read and --allow-fs-write restrictions using crafted relative symlink paths. By chaining directories and symlinks, a script granted access only to the current directory can escape the allowed path and read sensitive files. This breaks the expected isolation guarantees and enables arbitrary file read/write, leading to potential system compromise. This vulnerability affects users of the permission model on Node.js v20, v22, v24, and v25.