Vitest is a testing framework powered by Vite. Prior to versions 3.2.7, 4.1.10, and 5.0.0-beta.6, Browser Mode provider commands including upload, takeScreenshot, screenshotMatcher, stopChunkTrace, deleteTracing, and annotateTraces accept browser-supplied file paths without enforcing the allowWrite permission gate or confining paths to the project root. A client that can reach the Browser Mode API can read arbitrary local files, create or overwrite image and trace files, or delete files accessible to the Vitest process even when allowWrite is false. This issue is fixed in versions 3.2.7, 4.1.10, and 5.0.0-beta.6.

Affected: npm: @vitest/browser

## Summary

Browser Mode exposes a set of built-in "commands" that run on the Node.js side of the test runner and can touch the local filesystem (taking screenshots, managing Playwright traces, uploading files for `<input type="file">`, comparing screenshots).

Several of these commands accept a file path from the browser and act on it without checking the `allowWrite` permission gate and without confining the path to the project directory. A client that can reach the Browser Mode API can therefore read, create, overwrite, or delete files anywhere the Vitest process can access, even when `allowWrite` is `false`.

This matters most when the Browser Mode API is exposed to the network (for example `test.api.host` is set, or the dev server is reachable from another machine or origin). In that configuration `allowWrite` defaults to `false` precisely to block file access, and these commands bypass that protection. On a default localhost-only setup with trusted test code, there is no untrusted party in a position to exploit it. The gap still matters wherever you rely on `allowWrite: false` to contain untrusted test code, because these commands ignore that flag.

## Affected commands and impact

| Command | Operation | Impact | |---|---|---| | `upload` (Playwright + WebdriverIO) | Read | Arbitrary local file read; contents are loaded into the page and readable by test code. Highest-impact case. | | `takeScreenshot` (Playwright + WebdriverIO) | Write | Writes a PNG to an arbitrary pa…