Auth bypass in Nodejs Node

CVE-2026-21716

An incomplete fix for CVE-2024-36137 leaves `FileHandle.chmod()` and `FileHandle.chown()` in the promises API without the required permission checks, while their callback-based equivalents (`fs.fchmod()`, `fs.fchown()`) were correctly patched. As a result, code running under `--permission` with restricted `--allow-fs-write` can still use promise-based `FileHandle` methods to modify file permissions and ownership on already-open file descriptors, bypassing the intended write restrictions. This vulnerability affects **20.x, 22.x, 24.x, and 25.x** processes using the Permission Model where `--allow-fs-write` is intentionally restricted.

Vulnerability class: Broken Access Control

EPSS: 0.002 (5.5th percentile) — read the EPSS interpretation.