CVE-2025-61785: Deno's --deny-write check does not prevent permission bypass

Severity: low (CVSS 3.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2025-10-08 · updated 2026-10-08
Weakness: CWE-266

Description

Deno is a JavaScript, TypeScript, and WebAssembly runtime. In versions prior to 2.5.3 and 2.2.15, `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. Versions 2.5.3 and 2.2.15 fix the issue.

Affected products

denoland deno: through 2.2.15; from 2.3.0 before 2.5.3 — fixed in 2.5.3

How to fix

Upgrade to a fixed version: denoland deno 2.5.3. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2025-61785 or the next vulnerability affects your stack