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Response snapshot Oct 27, 2026, 03:07 UTC

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VulnerabilityCVE-2026-112948

Vitest: Servers misapply `server.fs.deny`, serving `.env`, private keys, `.git`, and the API token file

In Vitest 5, Vite's `server.fs.deny` is not applied as intended on Vitest's dev servers. Depending on the server, files that Vite refuses to serve by default (such as `.env`, private keys and certificates, `.npmrc`, and `.git`) or Vitest's own API token file (`.

Published Updated

At a glance

Exploited
Not known
Severity
6.5 Medium (CVSS 3.1)
Chance of exploitation
0.4% in the next 30 days
Sources
1 source

What to do

GitHub lists first patched versions: @vitest/ui: 5.0.5; @vitest/browser: 5.0.5; vite-plus: 1.3.0. Confirm the affected range and upgrade guidance in the exact advisory.

Read GitHub-reviewed advisory GHSA-p458-7748-mcp3 (opens a new tab)

What happened

### Summary

In Vitest 5, Vite's `server.fs.deny` is not applied as intended on Vitest's dev servers. Depending on the server, files that Vite refuses to serve by default (such as `.env`, private keys and certificates, `.npmrc`, and `.git`) or Vitest's own API token file (`.vitest-secret-token`) can be read over plain HTTP by a client that can reach the server. In Browser Mode with `test.projects`, a malicious website can also read `.env` values through the developer's browser.

This only applies when Vitest runs an HTTP server, which happens with the UI (`--ui`), Browser Mode, or `api` enabled. Plain `vitest` and `vitest run` don't listen on any port and are not affected. The fix ships in `vitest`, and `@vitest/ui` and `@vitest/browser` are listed because they are what enables the affected setups.

Both pin `vitest` to the same version as a peer dependency, so upgrading either one also requires the patched `vitest`. Users who enable `api` without `@vitest/ui` or `@vitest/browser` are also affected and should upgrade `vitest`.

Continue reading

### Details

Vitest 5 adds its API token file to `server.fs.deny`, but neither server ended up with the intended list. That's because of two Vite behaviors. Vite applies its default deny list only when `server.fs.deny` is unset, and it compiles the list into a matcher during config resolution, so later changes to the array have no effect.

| setup | listening server | Vite's default deny list | `.

vitest-secret-token` | | ---------------------------------- | ------------------------------- | ------------------------ | ----------------------------------- | | plain `vitest` / `vitest run` | none | not reachable | not reachable | | `--ui` or `api` | root | denied | **served** (fallback location only) | | Browser Mode, single project | root (also the browser server) | denied | **served** (fallback location only) | | Browser Mode with `test.

projects` | each browser project's server | **served** | denied |

- **Project servers** set `deny: ['.vitest-secret-token']` from a `config()` hook, which replaces Vite's defaults. A project server listens on a port in Browser Mode with `test.projects`, so in that setup a request like `GET /.env?raw` returns the file. A plain `GET /.env` is also served as `text/javascript`, so a malicious page can include it with ` /.env">`.

A classic script include needs no CORS, and each dotenv line whose value is valid JavaScript (a quoted string, number, or boolean) runs as a global assignment the page can read. A syntax error anywhere in the file, such as a `#` comment, keeps the whole script from running. The same missing defaults also loosen Browser Mode's file-access checks for `server.readFile`/`writeFile`/`removeFile`, screenshots, and traces.

- **The root server** adds the token entry after Vite has compiled the matcher, so the entry is never applied. The token file normally lives in the per-user data directory, which is outside `server.fs.allow`. When that directory can't be written, for example in a container whose user has no writable `HOME`, Vitest falls back to ` /node_modules/.vitest/.vitest-secret-token`, which the root server then serves.

The token authenticates the UI, `/__vitest_attachment__`, and the API WebSocket, whose RPC can write and rerun test files when `api.allowWrite`/`api.allowExec` are enabled.

### Impact

Information disclosure from the Vitest dev server, and with the token, privileged API access.

- **From a malicious website**, in Browser Mode with `test.projects`: while the browser server runs, any page the developer visits can read `.env` values that are valid JavaScript, through a classic ` ` include. This works when the file consists of `KEY="value"` lines. An unquoted value causes a runtime error that stops the script at that line, so only the lines before it leak.

A syntax error anywhere in the file, such as a `#` comment line or an `export` prefix, prevents the script from running at all. Recent Chrome versions may ask for Local Network Access permission first. `fetch` and XHR reads from other websites are still blocked by Vite's default CORS policy, and Vite's `Host` check blocks DNS rebinding.

That CORS policy does allow localhost origins, so a page served from another local dev server could read full files. The token file can't be read through a classic ` `, because a bare token isn't valid JavaScript. - **With local access or developer-set network exposure** (such as `api.host` or `browser.api.

host`, port forwarding, or a published container port): full file contents are readable over plain HTTP, including the token file when it's in the fallback location.

Only the machine running Vitest is exposed, while it runs one of the setups above. Applications built or deployed from the project aren't affected.

The fix is in `vitest` ` `. Vitest 4 and earlier are unaffected. They don't persist an API token, and they don't override `server.fs.deny`.

### Workaround

Set `server.fs.deny` explicitly in the root Vitest config, including Vite's default list for your Vite version and the token file. For Vite 8.3:

```ts export default defineConfig({ server: { fs: { deny: [ '.env', '.env.*', '*.{crt,pem,key,p12,pfx,cer,der}', '.npmrc', '.yarnrc.yml', '**/.git/**', '.vitest-secret-token', ], }, }, }) ```

Affected package ranges reported by GitHub: @vitest/ui: >= 5.0.0-beta.6, < 5.0.5 @vitest/browser: >= 5.0.0-beta.6, < 5.0.5 vite-plus: >= 1.0.0-rc.0, < 1.3.0

Scores and how they were measured

CVSS base severity

6.5

Version 3.1As of

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

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

0.4%

Scored Percentile 34.1%

Model and measurement source (opens a new tab)

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    GitHub-reviewed advisory GHSA-p458-7748-mcp3 (opens a new tab)

    The public advisory supplies the description, affected package/version ranges, and any listed CVSS metric. GitHub review is not local review.

    Published Checked

  2. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-p458-7748-mcp3, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  3. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-p458-7748-mcp3, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  4. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-p458-7748-mcp3, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  5. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-p458-7748-mcp3, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  6. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-p458-7748-mcp3, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  7. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-p458-7748-mcp3, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  8. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-p458-7748-mcp3, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  9. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-p458-7748-mcp3, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  10. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-p458-7748-mcp3, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  11. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-p458-7748-mcp3, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  12. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-112948, scored 2026-10-26. This is a model estimate, not proof of exposure.

    Published Checked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 21). Vitest: Servers misapply `server.fs.deny`, serving `.env`, private keys, `.git`, and the API token file (CVE-2026-112948). https://kevwire.com/record/CVE-2026-112948

MLA

"Vitest: Servers misapply `server.fs.deny`, serving `.env`, private keys, `.git`, and the API token file (CVE-2026-112948)." KEVWire, 21 Oct. 2026, kevwire.com/record/CVE-2026-112948.

Chicago

KEVWire. "Vitest: Servers misapply `server.fs.deny`, serving `.env`, private keys, `.git`, and the API token file (CVE-2026-112948)." Last modified October 21, 2026. https://kevwire.com/record/CVE-2026-112948.

Evidence summary (plain text)

Vitest: Servers misapply `server.fs.deny`, serving `.env`, private keys, `.git`, and the API token file (Oct 21, 2026).
In Vitest 5, Vite's `server.fs.deny` is not applied as intended on Vitest's dev servers. Depending on the server, files that Vite refuses to serve by default (such as `.env`, private keys and certificates, `.npmrc`, and `.git`) or Vitest's own API token file (`.vitest-secret-token`) can be read over plain HTTP by a client that can reach the server. In Browser Mode with `test.projects`, a malicious website can also read `.env` values through the developer's browser.

This only applies when Vitest runs an HTTP server, which happens with the UI (`--ui`), Browser Mode, or `api` enabled. Plain `vitest` and `vitest run` don't listen on any port and are not affected. The fix ships in `vitest`, and `@vitest/ui` and `@vitest/browser` are listed because they are what enables the affected setups. Both pin `vitest` to the same version as a peer dependency, so upgrading either one also requires the patched `vitest`. Users who enable `api` without `@vitest/ui` or `@vitest/browser` are also affected and should upgrade `vitest`.
CVSS 6.5 (version 3.1; evidence as of Oct 21, 2026; https://github.com/advisories/GHSA-p458-7748-mcp3).
EPSS 0.4% for the following 30 days, scored Oct 26, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-112948&date=2026-10-26).
Sources:
GitHub-reviewed advisory GHSA-p458-7748-mcp3: https://github.com/advisories/GHSA-p458-7748-mcp3
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMlQxNTo1Mjo1NlrOAAfxiA%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMlQxNDowNjoxNFrOAAfxZw%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMlQwODoyNzoyM1rOAAYp9A%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMTozNTo1OFrOAAfwCQ%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMTozMDoxM1rOAAfv2A%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMToyODowOVrOAAfv1g%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMToyNDoyMFrOAAfv1Q%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMDo0NTowN1rOAAfvzQ%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMDozMDoyNlrOAAfvxw%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yMVQyMDowMzo1N1rOAAfvxQ%3D%3D
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-112948&date=2026-10-26
Record ID: CVE-2026-112948.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 27, 2026, 01:40 UTC. Ingestion is not an independent editorial investigation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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