CVE-2025-61785 is a low-severity (CVSS 3.3) CWE-266 vulnerability in deno. O3 Security confirms whether CVE-2025-61785 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Deno's --deny-write check does not prevent permission bypass
Real-World Exposure
denoReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
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 Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | deno | all versions | 2.5.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for deno. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update deno to 2.5.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-61785 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2025-61785 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2025-61785. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2025-61785 in your dependencies?
O3 detects CVE-2025-61785 across crates.io dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.