CVE-2026-21716
Description
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.
How to fix CVE-2026-21716
To remediate CVE-2026-21716, upgrade the affected package to a fixed version below.
- —upgrade to 22.22.2-r0 or later
- —upgrade to 20.20.2 or later
- —upgrade to 20.20.2 or later
- —upgrade to 20.19.2+dfsg-1+deb13u2 or later
Is CVE-2026-21716 being exploited?
Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.
Affected packages (4)
- from 0, < 22.22.2-r0
- from 0, < 20.20.2, >= 21.0.0, < 22.22.2, >= 23.0.0, < 24.14.1, >= 25.0.0, < 25.8.2
- from 0, < 20.20.2, >= 21.0.0, < 22.22.2, >= 23.0.0, < 24.14.1, >= 25.0.0, < 25.8.2
- from 0, < 20.19.2+dfsg-1+deb13u2
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | LOW3.3 | CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N |