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CVE-2026-21716

low

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.

3.3
cvss low
common vulnerability scoring system v3.1. measures intrinsic severity on a 0-10 scale.
epss 0.0000
exploitation prediction scoring system. probability this vulnerability will be exploited in the wild in the next 30 days.
kev no
cisa known exploited vulnerabilities catalog. confirmed active exploitation.
CVSS 3.0 Common Vulnerability Scoring System v3.0
3.3 / 10
LOW
exploitability
Attack Vector
Local
Attack Vector (AV:L): requires local access. attacker must have shell access or physical login.
Attack Complexity
Low
Attack Complexity (AC:L): no special conditions needed. attack can be reliably reproduced.
Privileges Required
Low
Privileges Required (PR:L): requires basic user-level access.
User Interaction
None
User Interaction (UI:N): no victim action needed. fully exploitable without user interaction.
impact
Scope
Unchanged
Scope (S:U): impact limited to the vulnerable component.
Confidentiality
None
Confidentiality (C:N): no confidentiality impact.
Integrity
Low
Integrity (I:L): limited data modification. some data can be altered.
Availability
None
Availability (A:N): no availability impact.
CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
exploit detect attrib advisory media timeline
exploitation detection attribution advisories media timeline
activity density
rdintel assessment
16 threat composite score from 15+ signals including exploitation status, epss probability, detection coverage, and community attention. 0-100 scale.

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