Deno's --deny-write check does not prevent permission bypass

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

3.3 · CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

EPSS

• CVE-2025-61785: 0.20% estimated exploitation activity in the next 30 days; percentile 10.47 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary Deno.FsFile.prototype.utime and Deno.FsFile.prototype.utimeSync are not limited by the permission model check --deny-write=./. It's possible to change to change the access (atime) and modification (mtime) times on the file stream resource even when the file is opened with read only permission (and write: false) and file write operations are not allowed (the script is executed with --deny-write=./). Similar APIs like Deno.utime and Deno.utimeSync require allow-write permission, however, when a file is opened, even with read only flags and deny-write permission, it's still possible to change the access (atime) and modification (mtime) times, and thus bypass the permission model. PoC Setup: Output: - deno run --allow-read=./ --deny-write=./ pocfile.utime.ts 1 - deno run --allow-read=./ --deny-write=./ pocfile.utime.ts 2 - deno run --allow-read=./ --deny-write=./ pocfile.utime.ts 3 - deno run --allow-read=./ --deny-write=./ pocfile.utime.ts 4 Impact Permission model bypass

Published by the source

7 Oct 2025, 22:36 UTC

Last modified by the source

13 Oct 2025, 15:17 UTC

Source last checked

26 Oct 2026, 15:39 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-vg2r-rmgp-cgqj

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# Patch Next advisory brief: CVE-2025-61785

Advisory: Deno's --deny-write check does not prevent permission bypass
IDs: CVE-2025-61785, GHSA-vg2r-rmgp-cgqj
Record: https://patchnext.com/advisories/cve-2025-61785 (revision 1, source checked 26 Oct 2026, 15:39 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 3.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: deno 2.5.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io deno: affected < 2.5.3; fixed in 2.5.3

## Suggested inspection (read-only)
- crates.io deno: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on deno.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-vg2r-rmgp-cgqj (GitHub-reviewed advisory GHSA-vg2r-rmgp-cgqj lists affected ranges: crates.io deno >=0 <2.5.3)

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