Permission Model filesystem over-grant via wildcard radix lookup

Summary

A flaw in Node.js Permission Model filesystem enforcement can grant access to paths that do not match a wildcard --allow-fs-read or --allow-fs-write rule.

When the requested path is shorter than the prefix of a wildcard grant, the radix tree lookup stops comparing early and treats the path as a match. For example, --allow-fs-read=/etc/passwd.* also allows reading /etc/passwd. This requires the wildcard grant to sit directly under the root of the permission tree, for example when it is the only grant for that scope. This is a different root cause from CVE-2026-58043.

This vulnerability affects Node.js 26.x.