Improper Access Control in Node.js - CVE-2026-21716
Published: March 25, 2026
Vulnerability identifier: #VU124549
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-21716
CWE-ID: CWE-284
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vendor: Node.js Foundation
Affected software:
Node.js
Node.js
Detailed vulnerability description
The vulnerability allows a local user to modify file permissions and ownership.
The vulnerability exists due to improper access control in FileHandle.chmod() and FileHandle.chown() methods in the promises API when modifying file metadata. A local user can run code under --permission with restricted --allow-fs-write to use promise-based FileHandle methods and change permissions or ownership of already-open file descriptors, bypassing intended write restrictions.
This issue affects only environments using the Permission Model with --allow-fs-write intentionally restricted.
Note, the vulnerability exists due to incomplete fix for #VU93881 (CVE-2024-36137).
How to mitigate CVE-2026-21716
Install security update from vendor's website.