Node.js Permission Model bypass in FileHandle.chmod() and FileHandle.chown()
CVE-2026-21716 is a low-severity permission bypass in Node.js affecting the promises-based filesystem API under the Permission Model. It is described as an incomplete fix for CVE-2024-36137: while the callback-based equivalents fs.fchmod() and fs.fchown() were patched to enforce permission checks, the promises API methods FileHandle.chmod() and FileHandle.chown() remained without the required enforcement. As a result, code running in a Node.js process started with --permission and restricted --allow-fs-write can still use these promise-based FileHandle methods on already-open file descriptors to change file mode bits and ownership, bypassing the intended filesystem write restrictions. The issue affects Node.js 20.x, 22.x, 24.x, and 25.x processes using the Permission Model.
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A Node.js vulnerability caused by an incomplete patch for CVE-2024-36137, leaving FileHandle.chmod() and FileHandle.chown() in the promises API without proper permission enforcement.
A low-severity Node.js permission model bypass in lib/fs/promises that can disclose filesystem paths due to missing permission enforcement.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.