Nuxt dev server exposes private runtime config through the Nitro dev bundle

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

Nuxt is an open-source web development framework for Vue.js. From 3.0.0 until 4.6.3, the Nuxt development server can expose the Nitro 2 development bundle at <buildDir>/dev/index.mjs through Vite file serving when the server is reachable over HTTP. Nitro inlines private runtimeConfig values resolved at build time into that bundle, including secrets configured in nuxt.config, and Nuxt 4.6.0 and later also inline the generated development appSecret. The default localhost binding limits remote exposure, production builds and Nitro 3 are not affected, and runtime configuration supplied only through NUXT_* environment variables at server startup is not inlined. This issue is fixed in version 4.6.3.

Source published

29 Oct 2026 20:14:07 UTC

Source modified

29 Oct 2026 20:27:59 UTC

Observed here

29 Oct 2026 21:48:56 UTC

Source terms

CVE Program Terms of Use

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Nuxt is an open-source web development framework for Vue.js. From 3.0.0 until 4.6.3, the Nuxt development server can expose the Nitro 2 development bundle at <buildDir>/dev/index.mjs through Vite file serving when the server is reachable over HTTP. Nitro inlines private runtimeConfig values resolved at build time into that bundle, including secrets configured in nuxt.config, and Nuxt 4.6.0 and later also inline the generated development appSecret. The default localhost binding limits remote exposure, production builds and Nitro 3 are not affected, and runtime configuration supplied only through NUXT_* environment variables at server startup is not inlined. This issue is fixed in version 4.6.3.

Source published

Oct 29, 2026, 8:14:07 PM (timezone not stated)

Source modified

Oct 29, 2026, 8:27:59 PM (timezone not stated)

Observed here

6 Nov 2026 01:44:45 UTC

Source terms

ENISA EUVD · source terms and attribution apply

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 3.1 · 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Nuxt is an open-source web development framework for Vue.js. From 3.0.0 until 4.6.3, the Nuxt development server can expose the Nitro 2 development bundle at <buildDir>/dev/index.mjs through Vite file serving when the server is reachable over HTTP. Nitro inlines private runtimeConfig values resolved at build time into that bundle, including secrets configured in nuxt.config, and Nuxt 4.6.0 and later also inline the generated development appSecret. The default localhost binding limits remote exposure, production builds and Nitro 3 are not affected, and runtime configuration supplied only through NUXT_* environment variables at server startup is not inlined. This issue is fixed in version 4.6.3.

Source published

29 Oct 2026 21:17:18 UTC

Source modified

30 Oct 2026 17:18:03 UTC

Observed here

30 Oct 2026 23:47:40 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

### Summary With Nitro 2 (the default server engine in Nuxt 3 and Nuxt 4), the Nitro development server bundle written by `nuxt dev` can be fetched through the Vite dev server. Nitro inlines the resolved `runtimeConfig` into that bundle, so private runtime config values that were resolved at build time can be read by anyone with HTTP access to the dev server. ### Impact `nuxt dev` writes the Nitro development server bundle to `<buildDir>/dev/index.mjs` (by default `.nuxt/dev/index.mjs`). The build directory is inside the directories Nuxt passes to Vite's `server.fs.allow`, so the bundle is served by the dev server: ```bash curl http://<dev-server>/_nuxt/@fs/<absolute-path-to-project>/.nuxt/dev/index.mjs ``` The response contains every private (non-`public`) runtime config value that was resolved at build time. That includes values set in `nuxt.config`, such as a secret read from `.env`: ```ts export default defineNuxtConfig({ runtimeConfig: { apiSecret: process.env.API_SECRET, }, }) ``` From Nuxt 4.6.0, it also includes the generated development `appSecret`. Vite's default deny list blocks `.env` itself, but not the bundle containing values read from it. Exploitation requires direct HTTP access to the dev server. `nuxt dev` listens on localhost by default, so this mainly affects dev servers that are exposed to a network (for example with `--host`, a published container port or a tunnel). As far as we can tell, a malicious website cannot read the file through a developer's browser: Vite's CORS and host checks prevent pages on other origins from reading the response. Production builds are not affected, because the Vite dev server is not used and the server bundle is not served. Nuxt projects using Nitro 3 do not write the server bundle to disk in development and are not affected. Private runtime config values that are left empty in `nuxt.config` and supplied through `NUXT_*` environment variables are applied when the server starts, are not inlined into the bundle, and are not exposed. ### Patches Fixed in `@nuxt/vite-builder` 4.6.3, which `nuxt` 4.6.3 depends on. The dev server now adds Nitro's development output directory to Vite's `server.fs.deny`, keeping Vite's default deny list. Nuxt 3 has reached end of life and will not receive a fix. ### Workarounds Avoid exposing the dev server to untrusted networks. Alternatively, set private runtime config keys to an empty default in `nuxt.config` and provide their values with the matching `NUXT_*` environment variables (for example `runtimeConfig: { apiSecret: '' }` with `NUXT_API_SECRET` in `.env`). If a dev server has been reachable by untrusted clients, rotate any credentials that were set through `runtimeConfig` in `nuxt.config`.

Source published

30 Oct 2026 23:00:43 UTC

Source modified

30 Oct 2026 23:15:08 UTC

Observed here

30 Oct 2026 23:45:44 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Publisher rating · MODERATE