Vitest Browser: Exposed Browser Mode API Can Proxy CDP and Overwrite Config Files, Leading to RCE

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

9.8 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

• CVE-2026-53633: 0.90% estimated exploitation activity in the next 30 days; percentile 59.59 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary Vitest Browser Mode exposes a cdp() API that forwards raw Chrome DevTools Protocol (CDP) methods over the Vitest browser WebSocket RPC. CDP is not gated by browser.api.allowWrite, browser.api.allowExec, api.allowWrite, or api.allowExec. As a result, disabling Browser Mode write and exec operations does not prevent a browser API client from using CDP to perform equivalent actions. In a verified reproduction with allowWrite: false and allowExec: false, CDP Page.setDownloadBehavior set the browser download directory to the project root, and CDP Runtime.evaluate downloaded a controlled vite.config.ts. Vitest reloaded the changed config and executed attacker-controlled Node.js code. When the Browser Mode API is also exposed to the network, this becomes remotely exploitable because the generated browser runner page exposes the API token, active session id, project name, and project root path needed to connect to the browser WebSocket API and select the target download directory.…

Published by the source

15 Jun 2026, 20:05 UTC

Last modified by the source

13 Aug 2026, 18:30 UTC

Source last checked

26 Oct 2026, 13:01 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-g8mr-85jm-7xhm

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-g8mr-85jm-7xhm

3. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-g8mr-85jm-7xhm

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# Patch Next advisory brief: CVE-2026-53633

Advisory: Vitest Browser: Exposed Browser Mode API Can Proxy CDP and Overwrite Config Files, Leading to RCE
IDs: CVE-2026-53633, GHSA-g8mr-85jm-7xhm
Record: https://patchnext.com/advisories/cve-2026-53633 (revision 3, source checked 26 Oct 2026, 13:01 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @vitest/browser 5.0.0-beta.4, 4.1.8, 3.2.5; vite-plus 0.1.24. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @vitest/browser: affected >= 5.0.0-beta.0, <= 5.0.0-beta.3; >= 4.0.0, <= 4.1.7; >= 3.0.0, <= 3.2.4; fixed in 4.1.8, 5.0.0-beta.4, 3.2.5
- npm vite-plus: affected <= 0.1.23; fixed in 0.1.24

## Suggested inspection (read-only)
- `npm ls @vitest/browser --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.
- `npm ls vite-plus --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @vitest/browser, vite-plus.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-g8mr-85jm-7xhm (GitHub-reviewed advisory GHSA-g8mr-85jm-7xhm lists affected ranges: npm @vitest/browser >=5.0.0-beta.0 =4.0.0 =3.0.0 =0 <=0.1.23)
- Verified: https://osv.dev/vulnerability/GHSA-g8mr-85jm-7xhm (OSV record GHSA-g8mr-85jm-7xhm lists affected ranges: npm @vitest/browser >=5.0.0-beta.0 =4.0.0 =3.0.0 =0 <0.1.24 (fixed))

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