CVE-2026-73653: @vitest/browser: Browser Mode provider commands bypass the file-access permission gate

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 0.8%, percentile 56: FIRST’s model estimates a 0.8% chance of exploitation activity in the next 30 days, higher than 56% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes @vitest/browser (npm) >= 4.0.0, < 4.1.10, fixed in 4.1.10; @vitest/browser (npm) < 3.2.7, fixed in 3.2.7; @vitest/browser (npm) >= 5.0.0-beta.1, < 5.0.0-beta.6, fixed in 5.0.0-beta.6. Check your lockfile, including transitive dependencies.

What it is

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.

From the GitHub advisory

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 , 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

Weakness type: CWE-22, CWE-552, CWE-862.

Product: @vitest/browser (npm) · Assigned by: GitHub_M · Published: 2026-08-13

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: none (no login)
• User interaction: none
• Scope: unchanged

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.79% probability of exploitation activity in the next 30 days; percentile 56.

Timeline

• 2026-07-21 — GitHub-reviewed advisory GHSA-p63j-vcc4-9vmv published (critical)
• 2026-08-13 — CVE record last updated
• 2026-08-13 — CVE record published by GitHub_M

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-p63j-vcc4-9vmv github.com
2. CVE.org record CVE-2026-73653 cve.org
3. NVD entry CVE-2026-73653 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
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10. github.com github.com

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